Method of peeling off and method of manufacturing semiconductor device

ABSTRACT

The invention aims to provide a peeling method without damaging a peeled off layer and to allow separation of not only a peeled off layer having a small surface area but also the entire surface of a peeled off layer having a large surface area. Further, the invention aims to provide a lightweight semiconductor device by sticking a peeled off layer to a variety of substrates and its manufacturing method. Especially, the invention aims to provide a lightweight semiconductor device by sticking a variety of elements such as TFT to a flexible film and its manufacturing method. Even in the case a first material layer  11  is formed on a substrate and a second material layer  12  is formed adjacently to the foregoing first material layer  11 , and further, layered film formation, heating treatment at 500° C. or higher or laser beam radiating treatment is carried out, if the first material layer has a tensile stress before the peeling and the second material layer has a compressive stress, excellent separation can easily be carried out by physical means in the interlayer or interface of the second material layer  12.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a peeling method of a peeled off layer,especially, a peeling method of a peeled off layer containing variouselements. In addition to that, the present invention relates to asemiconductor device comprising a circuit composed of a thin filmtransistor (hereinafter referred to as TFT) transferred by sticking aseparated peeled off layer to a substrate and its manufacturing method.The invention relates, for example, an electrooptical device such as aliquid crystal module, a light emitting device such as an EL module, andan electronic appliance containing such devices as components therein.

The term semiconductor device, in this specification, covers any deviceas a whole capable of functioning by utilizing semiconductorcharacteristics and an electrooptical device, a light emitting device, asemiconductor circuit, and electronic apparatus are all included in thesemiconductor device.

2. Related Art

Recently, attention has been paid to a technology of composing a thinfilm transistor (TFT) using a semiconductor thin film (the thickness ofabout several to several hundred nm) formed on a substrate having aninsulating surface. The thin film transistor is widely applied toelectronic devices such as IC and an electrooptical device. Especially,its development as a switching element for an image display apparatushas been urged.

Among a variety of expected applications of such an image displayapparatus, above all, utilization for mobile appliances draws attention.Today, although a glass substrate, a quartz substrate and the like areused in many cases, they have disadvantages that they are easy to crackand heavy. Further, in terms of mass production, the glass substrate,the quartz substrate and the like are difficult and unsuitable forenlargement. Therefore, it is tried to use a substrate havingflexibility, such as a flexible plastic film to form a TFT elementthereon.

However, since the heat resistance of the plastic film is low, thehighest temperature for process is required to be low and consequently,it is presently impossible to form any TFT with electric characteristicsas excellent as those formed on a glass substrate. Hence, no liquidcrystal display apparatus and light emitting element using a plasticfilm has been actualized.

Further, a peeling method for peeling from the said substrate a peeledoff layer existing on a substrate through an isolation layer, has beenalready proposed. For example, a technique described in JapaneseUnexamined Patent Publication No.10-125929 and Japanese UnexaminedPatent Publication No. 10-125931 is a method for separating a substrateby forming an isolation layer of amorphous silicon (or polycrystallinesilicon) and releasing hydrogen contained in the amorphous silicon byradiating laser beam through a substrate to form voids for substrateseparation. In addition to that, in Japanese Unexamined PatentPublication No.10-125930, there is a description that using thistechnique, a liquid crystal display apparatus is completed by sticking apeeled off layer (in the specification, called as a transferred layer)to a plastic layer.

However, by the above-described method, it is essential to use asubstrate with high translucency. In order to transmit energy throughthe substrate and supply energy sufficient to release hydrogen containedin the amorphous silicon, relatively intense laser beam has to beradiated, resulting in a problem that the peeled off layer is damaged.Further, by the above-described method, in the case an element is formedon an isolation layer, if heating treatment at a high temperature iscarried out in the element fabrication process, hydrogen contained inthe isolation layer is diffused and decreased. As a result, there is apossibility of insufficient peeling-off, even if laser beam is radiatedto the isolation layer. Subsequently, attributed to retention of thequantity of hydrogen contained in the isolation layer, there occurs aproblem that the process after isolation layer formation may be limited.Also, in the above-described specification, there is a description thatin order to prevent damages in the peeled off layer, a light shieldinglayer or reflecting layer is formed. In such a case, it becomesdifficult to fabricate a transmission type liquid crystal displayapparatus. Additionally, by the above-described method, peeling of thepeeled off layer having a large surface area becomes difficult.

SUMMARY OF THE INVENTION

The invention has been completed in consideration of the above-describedproblems and the invention aims to provide a peeling method withoutdamaging a peeled off layer and to allow separation of not only a peeledoff layer having a small surface area but also the entire surface of apeeled off layer having a large surface area.

Further, the invention aims to provide a peeling method in which thetype or the like of a substrate is not limited in formation of a peeledoff layer.

Further, the invention aims to provide a lightweight semiconductordevice by sticking a peeled off layer to a variety of substrates and itsfabrication method. Especially, the invention aims to provide alightweight semiconductor device by sticking a variety of elements suchas TFT [a thin film diode, a photoelectric conversion element (a solarcell, a sensor and the like) comprising PIN junction of silicon, andsilicon resistor element] to a flexible film and its fabrication method.

Inventors of the invention have made experiments and investigationsrepeatedly, and found out the following. That is, when a first materiallayer is formed on a substrate and a second material layer is formedadjacently to the first material layer and further film formation orheating treatment at 500° C. or higher is carried out on or for thesecond material layer and then, according to measurement of the internalstress of the respective films, the first material layer has a tensilestress and the second material layer has a compressive stress. The layerstructure of the first material layer and the second material layercauses no abnormality such as a film peeling-off (peeling) in theprocess, whereas the layer structure can be separated well in theinterlayer or interface of the second material layer easily by physicalmeans such as application of mechanical force, for example peeling by aman with hands.

That is, the bonding force of the first material layer and the secondmaterial layer is strong enough to withstand the heat energy and on theother hand, immediately before the peeling-off, the first material layerhaving the tensile stress and the second material layer having thecompressive stress has the stress strain between them, so that they areweak to mechanical energy and easily separated. Inventors of theinvention have found that there is a close relation between the peelingphenomenon and the internal stress of a film. The peeling step forcarrying out separation using the internal stress of a film is called astress peeling-off process.

A constitution 1 of the invention relevant to a peeling method disclosedin this specification is a peeling method for peeling a peeled off layerfrom a substrate. It is characterized in that the method comprises stepsof forming the peeled off layer composed of a first material layerhaving a tensile stress on the substrate and a second material layerhaving a compressive stress and neighboring at least the first materiallayer on the substrate bearing the first material layer thereon and thenpeeling the peeled off layer from the substrate bearing the firstmaterial layer by physical means in the interlayer or interface of thesecond material layer.

In the above-described constitution 1, the foregoing first materiallayer is characterized in that the layer has a tensile stress in a rangeof 1 to 1×10¹⁰ (Dyne/cm²). The foregoing first material layer is notparticularly limited if the material has a tensile stress within theforegoing range and a monolayer of any one of a metal material (Ti, Al,Ta, W, Mo, Cu, Cr, Nd, Fe, Ni, Co, Zr, Zn, Ru, Rh, Pd, Os, Ir, Pt andthe like), a semiconductor material (e.g. Si, Ge and the like), aninsulating material, and an organic material or their laminated layermay be employed. Incidentally, a film having a tensile stress higherthan 1×10¹⁰ (Dyne/cm²) is easy to cause peeling in the case of heatingtreatment.

Further, in the above-described constitution 1, the foregoing secondmaterial layer is characterized in that the layer has a compressivestress in a range of −1 to −1×10¹⁰ (Dyne/cm²). The foregoing secondmaterial layer is not particularly limited if the material has acompressive stress within the foregoing range and a monolayer of any oneof a metal material (Ti, Al, Ta, W, Mo, Cu, Cr, Nd, Fe, Ni, Co, Zr, Zn,Ru, Rh, Pd, Os, Ir, Pt and the like), a semiconductor material (e.g. Si,Ge and the like), an insulating material, and an organic material ortheir laminated layer may be employed. Incidentally, a film having acompressive stress higher than −1×10¹⁰ (Dyne/cm²) is easy to causepeeling in the case of heating treatment.

Further, for the first material layer, a material may be used if thematerial has a tensile stress immediately before the peeling, even if itshows a compressive stress immediately after formation. Constitution 2of the invention relevant to a peeling method disclosed in thisspecification, is a peeling method for peeling a peeled off layer from asubstrate. It is characterized in that the method comprises steps offorming the peeled off layer composed of a first material layer on thesubstrate and a second material layer having a compressive stress andneighboring at least the first material layer on the substrate bearingthe first material layer thereon and then peeling the peeled off layerfrom the substrate bearing the first material layer by physical means inthe interlayer or interface of the second material layer.

In the above-described constitution 2, the foregoing first materiallayer is characterized in that the layer has a tensile stress in a rangeof 1 to 1×10¹⁰ (Dyne/cm²).

In the above-described constitution 2, heating treatment or laser beamradiating treatment is carried out before peeling.

Further, also in the above-described constitution 2, the foregoingsecond material layer is characterized in that it has a compressivestress in a range of −1 to 1×10¹⁰ (Dyne/cm²).

Further, the peeling may be carried out after a supporting body is stuckwith an adhesive. Constitution 3 of the invention relevant to a peelingmethod disclosed in this specification, is a peeling method for peelinga peeled off layer from a substrate. It is characterized in that themethod comprises steps of forming the peeled off layer composed of afirst material layer having a tensile stress on the substrate and asecond material layer having a compressive stress and neighboring atleast the first material layer on the substrate bearing the firstmaterial layer thereon, sticking a supporting body to the peeled offlayer, and then peeling the peeled off layer stuck to the supportingbody from the substrate bearing the first material layer by physicalmeans in the interlayer or interface of the second material layer.

In the case a material having a tensile stress immediately beforepeeling is used as the first material layer, even if it shows acompressive stress immediately after formation, a constitution 4 of theinvention relevant to a peeling method disclosed in this specification,is a peeling method for peeling a peeled off layer from a substrate. Itis characterized in that the method comprises steps of forming thepeeled off layer composed of a first material layer on the substrate anda second material layer having a compressive stress and neighboring atleast the first material layer on the substrate bearing the firstmaterial layer thereon, sticking a supporting body to the peeled offlayer, and then peeling the peeled off layer from the substrate bearingthe first material layer by physical means in the interlayer orinterface of the second material layer.

Further in the foregoing constitution 3 and the foregoing constitution4, in order to promote the peeling before adhesion to the foregoingsupporting body, heating treatment or laser beam radiating treatment maybe carried out. In such a case, a material absorbing laser beam may beselected for the first material layer and the first material layer maybe heated so as to change the internal stress of the film to makepeeling easy. Nevertheless, in the case of using laser beam, atranslucent substrate is employed.

Further, in the respective constitutions, another layer, for example, aninsulating layer, a metal layer and the like, may be formed between thesubstrate and the first material layer to improve the adhesion strength.However, for simplification of the process, the first material layer ispreferable to be formed while being brought into contact with thesubstrate.

In this specification, the term physical means, denotes means regardedas not chemical but physical means and more particularly, dynamic meanscomprising a process deduced to dynamics rules or mechanical means anddenotes means for converting any dynamics energy (mechanical energy).

Incidentally, both of the above-described constitutions 3 and 4, at thetime of peeling by physical means, it is required to make the bondingforce of the first material layer and the second material layer lowerthan that to the supporting body.

Further, in the above-described invention, not only a substrate havingtranslucency but also any kind of substrate, for example, a glasssubstrate, a quartz substrate, a semiconductor substrate, a ceramicsubstrate, and a metal substrate, maybe used and a peeled off layerformed on a substrate can be peeled off.

Further, employing the above-described peeling method of the invention,it is possible to fabricate a semiconductor device by sticking(transferring) a peeled off layer formed on a substrate to a transferbody and a constitution of the invention relevant to a semiconductordevice manufacturing method is a semiconductor device manufacturingmethod comprising steps of forming a first material layer having tensilestress on a substrate, forming a second material layer having acompressive stress on the first material layer, forming an insulatinglayer on the second material layer, forming an element on the insulatinglayer, sticking a supporting body on the element and successivelypeeling the supporting body off the substrate by physical means in theinterlayer or the interface of the second material layer, and sticking atransfer body to the insulating layer or the second material layer andsandwiching the element between the supporting body and the transferbody.

In the case where a material having a tensile stress immediate beforepeeling is used as the first material layer, even if it has acompressive stress immediately after formation, the constitution of theinvention relevant to the semiconductor device manufacturing methoddisclosed in this specification, is a semiconductor device manufacturingmethod comprising steps of forming a first material layer on asubstrate, forming a second material layer having a compressive stresson said first material layer, forming an insulating layer on said secondmaterial layer, forming an element on said insulating layer, sticking asupporting body on said element and successively peeling said supportingbody from said substrate by physical means in the interlayer or theinterface of said second material layer, and sticking a transfer body tosaid insulating layer or said second material layer and sandwiching saidelement between said supporting body and said transfer body.

Further, in order to promote the peeling, a granular oxide may be formedon the first material layer and the second material layer covering thegranular oxide may be formed to make peeling easy.

In the above-described constitution, in order to promote the peelingfurther before adhesion of the foregoing supporting body, heatingtreatment or laser beam radiating treatment may be carried out. In sucha case, a material absorbing laser beam may be selected for the firstmaterial layer and the first material layer may be heated so as tochange the internal stress of the film to make peeling easy.Nevertheless, in the case of using laser beam, a translucent substrateis employed.

Further, by employing the above-described peeling method of theinvention, it is possible that after being peeled, the peeled off layerformed on the substrate is stuck to a first transfer body and a secondtransfer body to fabricate a semiconductor device.

Further, in the foregoing respective constitutions relevant to theabove-described semiconductor device manufacturing method, the foregoingelement is a thin film transistor having a semiconductor layer as anactive layer and the foregoing step of forming the semiconductor layeris carried out by crystallizing a semiconductor layer having anamorphous structure by heating treatment or laser beam radiatingtreatment to crystallize and form the semiconductor layer having acrystalline structure.

In this specification, the term transfer body, means a material to bestuck to the peeled off layer after being peeled and it is notparticularly limited and may be a substrate of any composition such asplastics, glass, metals, ceramics and the like. Also, in thisspecification, the term supporting body, means a material to be stuck tothe peeled off layer at the time of peeling by physical means. It is notparticularly limited and may be a substrate of any composition such asplastics, glass, metals, ceramics and the like. Further, the shape ofthe transfer body and the shape of the supporting body are notparticularly limited and may have a flat, curved, flexible, or film-likeshape. If the lightweight property receives the first priority, apreferable one is a film-like plastic substrate such as plastics ofpolyethylene terephthalate (PET), polyether sulfone (PES), polyethylenenaphthalate (PEN), polycarbonate (PC), nylon, polyether ether ketone(PEEK), polysulfone (PSF), polyether imide (PEI), polyarylate (PAR),polybutylene terephthalate (PBT), and the like.

In the above-described respective constitutions relevant to theabove-described semiconductor device manufacturing method, in the caseof fabricating a liquid crystal display apparatus, a supporting body isused as a counter substrate and a seal material is used as an adhesiveto stick the supporting body to a peeled off layer. In such a case, theelement formed in the foregoing peeling-off layer has a pixel electrodeand a liquid crystal is packed between the pixel electrode and theforegoing counter electrode

Further, in the above-described respective constitutions relevant to theabove-described semiconductor device manufacturing method, in the caseof fabricating alight emitting apparatus such as an EL light emittingdevice, it is preferable to use a seal material as a supporting body tocompletely shut the light emitting element out of the outside in amanner that outside substances such as water and oxygen which acceleratedeterioration of an organic compound layer are prevented frompenetration. If a lightweight property receives the first priority, afilm-like plastic substrate is preferable, however it is inferior toprevent substances such as water and oxygen of the outside whichaccelerate deterioration of an organic compound layer from penetrationand therefore, a first insulating film, a second insulating film, and athird insulating film may be formed on a supporting body so as tosufficiently prevent penetration of substances such as water and oxygenof the outside which accelerate deterioration of an organic compoundlayer from penetration. Nevertheless, the foregoing second insulatingfilm (a stress moderating film) sandwiched between the foregoing firstinsulating film (a barrier film) and the foregoing third insulating film(a barrier film) is made to have a lower film stress than that of theforegoing first and third insulating films.

In the case of fabricating a light emitting apparatus such as an ELlight emitting device, not only for the supporting body but also fortransfer body, it is preferable to similarly form a first insulatingfilm, a second insulating film, and a third insulating film tosufficiently prevent penetration of substances such as water and oxygenof the outside which accelerate deterioration of an organic compoundlayer from penetration.

In this specification, the internal stress of a film means, taking anyoptional cross-section of the inside of the film formed on a substrateinto consideration, the force per unit cross-section surface areatherewith one side of the cross-section affects the other side. It canbe said that the internal stress is inevitably caused more or less in athin film formed by vacuum evaporation, sputtering, and vapor phasedeposition. The value reaches at the maximum 10⁹ N/m². The internalstress value changes depending on a material of the thin film, asubstance of a substrate, and the formation condition of the thin film.Also, heating treatment changes the internal stress value.

Further, the state that the force affects a counterpart through a unitcross-section surface area perpendicular to a substrate face in thepulling direction is called as the tensile state and the internal stressin such a case is called as tensile stress, whereas the state that theforce affects in the pushing direction is called as the compressivestate and the internal stress in such a case is called as compressivestress. Incidentally, in this specification, the tensile stress is setto be positive (+) and the compressive stress to be negative (−) ingraphs and tables.

(Experiment 1)

Using titanium nitride for a first material layer and silicon oxide fora second material layer, the second material layer is formed whilecontacting the first material layer. In order to confirm whether apeeled off layer formed on the second material layer could be peeledfrom a substrate or not, the following experiment is carried out.

At first, a layered structure illustrated in FIG. 3A is formed on asubstrate.

As a substrate 30, a glass substrate (#1737) is used. Also, on thesubstrate 30, an aluminum-silicon alloy layer 31 with a film thicknessof 300 nm is formed by a sputtering method. Next, a titanium nitridelayer 32 with a film thickness of 100 nm is formed by a sputteringmethod.

Next, a silicon oxide layer 33 with a film thickness of 200 nm is formedby a sputtering method. The film formation of the silicon oxide layer 33is carried out under the conditions using an RF type sputteringapparatus and a silicon oxide target (diameter of 30.5 cm) at 150° C.substrate temperature, 0.4 Pa film formation pressure, 3 kW filmformation power, and 35 sccm/15 sccm=argon flow rate/oxygen flow rate.

Next, underlying insulating layer is formed on the silicon oxide layer33 by plasma CVD method. As the underlying insulating layer is formed asilicon nitride oxide film 34 a (composition ratio Si=32%, O=27%, N=24%,and H=17%) with a thickness of 50 nm from raw material gases of SiH₄,NH₃, and N₂O at a film formation temperature of 300° C. by a plasma CVDmethod. After that, the surface is washed with ozone water and then, anoxide film on the surface is removed by a diluted hydrofluoric acid(1/100 dilution). Next, a silicon nitride oxide film 34 b (compositionratio Si=32%, O=59%, N=7%, and H=2%) with a thickness of 100 nm islayered thereon using raw material gases of SiH₄ and N₂O at a filmformation temperature of 300° C. by a plasma CVD method and further asemiconductor layer (in this case an amorphous silicon layer 35) havingan amorphous structure and a thickness of 54 nm is formed using a filmformation gas of SiH₄ at a film formation temperature of 300° C. by aplasma CVD method without opening to the atmospheric air (FIG. 3A).

Next, a nickel acetate solution containing nickel in 10 ppm on the basisof weight is coated by a spinner. In place of coating, a method forspreading nickel element to the entire surface by sputtering might beemployed. Then, heating treatment is carried out for crystallization toform a semiconductor film (in this case, a polysilicon layer 36) havinga crystal structure (FIG. 3B). Here, after heating treatment (500° C.for 1 hour) for dehydrogenation, heating treatment for thecrystallization (550° C. for 4 hours) is carried out to obtain a siliconfilm with a crystal structure. Incidentally, in this case, acrystallization technique using nickel as a metal element for promotingcrystallization of silicon is employed, other well-known crystallizationtechnique, for example, a solid-phase growth method and a lasercrystallization method may be employed.

Next, using epoxy resin for an adhesive layer 37, a film substrate 38(in this case, polyethylene terephthalate (PET)) is stuck to thepolysilicon layer 36 (FIG. 3C).

After the state shown in FIG. 3C is achieved, the film substrate 38 andthe substrate 30 are pulsed by man's hands so as to separate them fromeach other. In the peeled substrate 30, at least titanium nitride andaluminum-silicon alloy layers are found remained. According to thisexperiment, it is supposed that the peeling took place in the interlayeror the interface of the silicon oxide 33.

As described above, it is made possible to peel the peeled off layer inthe entire face from the substrate 30 by forming the second materiallayer adjacently to the first material layer and peeling the peeled offlayer formed on the second material layer.

(Experiment 2)

Here, in the case of using TiN, W, WN, Ta, and TaN as the first materiallayer, the second material layer (silicon oxide: 200 nm film thickness)is formed while contacting the first material layer and in order toconfirm whether a peeled off layer formed on the second material layercould be peeled off a substrate or not, the following experiment iscarried out.

As a sample 1, TiN with a film thickness of 100 nm is formed on a glasssubstrate by a sputtering method and after that, a silicon oxide filmwith a film thickness of 200 nm is formed. After the formation of thesilicon oxide film, layering and crystallization are carried outsimilarly to the experiment 1.

As a sample 2, after W with a film thickness of 50 nm is formed on aglass substrate by a sputtering method and after that, a silicon oxidefilm with a film thickness of 200 nm is formed. After the formation ofthe silicon oxide film, layering and crystallization are carried outsimilarly to the experiment 1.

As a sample 3, after WN with a film thickness of 50 nm is formed on aglass substrate by a sputtering method and after that, a silicon oxidefilm with a film thickness of 200 nm is formed. After the formation ofthe silicon oxide film, layering and crystallization are carried outsimilarly to the experiment 1.

As a sample 4, after TiN with a film thickness of 50 nm is formed on aglass substrate by a sputtering method and after that, a silicon oxidefilm with a film thickness of 200 nm is formed. After the formation ofthe silicon oxide film, layering and crystallization are carried outsimilarly to the experiment 1.

As a sample 5, after Ta with a film thickness of 50 nm is formed on aglass substrate by a sputtering method and after that, a silicon oxidefilm with a film thickness of 200 nm is formed. After the formation ofthe silicon oxide film, layering and crystallization are carried outsimilarly to the experiment 1.

As a sample 6, after TaN with a film thickness of 50 nm is formed on aglass substrate by a sputtering method and after that, a silicon oxidefilm with a film thickness of 200 nm is formed. After the formation ofthe silicon oxide film, layering and crystallization are carried outsimilarly to the experiment 1.

In the samples 1 to 6 are formed in above-described manner, an adhesivetape is stuck to each peeled off layer to carry out an experiment toconfirm whether peeling is possible or not. The results are shown inTable 1.

TABLE 1 First material layer Second material layer (underlayer) (upperlayer) Tape test Sample 1 TiN (100 nm) Silicon oxide (200 nm) PeeledSample 2 W (50 nm) Silicon oxide (200 nm) Peeled Sample 3 WN (50 nm)Silicon oxide (200 nm) Peeled Sample 4 TiN (50 nm) Silicon oxide (200nm) Not peeled Sample 5 Ta (50 nm) Silicon oxide (200 nm) Not peeledSample 6 TaN (50 nm) Silicon oxide (200 nm) Not peeled

Further, regarding each of the silicon oxide film, TiN film, W film, andTa film, the internal stress is measured before and after heatingtreatment (550° C., 4 hours). The results are shown in Table 2.

TABLE 2 Internal stress value of a film (dyne/cm²) After film formationAfter heating treatment Silicon oxide film −9.40E+08  −1.34E+09 −9.47E+08  −1.26E+09  TiN film 3.90E+09 4.36E+09 3.95E+09 4.50E+09 Wfilm −7.53E+09  8.96E+09 −7.40E+09  7.95E+09 Ta film 9.23E+09 −7.84E+09 5.16E+09 −1.95E+10 

Incidentally, the silicon oxide film formed in a film thickness of 400nm on a silicon substrate by a sputtering method is subjected for themeasurement and regarding the TiN film, W film, and Ta film, after filmformation in a film thickness of 400 nm of a glass substrate, theinternal stress is measured and then, after a silicon film as a cap filmis layered and heating treatment is carried out, the cap film is removedand again the internal stress is measured. Also, each two specimens areproduced for every sample to carry out the measurement.

Regarding the W film, although the film had a compressive stress (about−7×10⁹ (Dyne/cm²)) immediately after the film formation and becomes afilm having a tensile stress (about 8×10⁹ to 9×10⁹ (Dyne/cm²)) by theheating treatment and the peeling state is excellent. Regarding the TiNfilm, the stress scarcely changed before and after the heating treatmentand the film had a tensile stress (about 3.9×10⁹ to 4.5×10⁹ (Dyne/cm²))with little alteration. However, in the case where the film thickness is50 nm or thinner, peeling is inferior. Regarding the Ta film, althoughthe film had a tensile stress (about 5.1×10⁹ to 9.2×10⁹ (Dyne/cm²))immediately after the film formation and becomes a film having acompressive stress (about −2×10⁹ to −7.8×10⁹ (Dyne/cm²)) by the heatingtreatment and is not peeled by the tape test. Further, regarding thesilicon oxide film, the stress scarcely changed before and after theheating treatment and the film had a compressive stress (about −9.4×10⁸to −1.3×10⁹ (Dyne/cm²)) with little alteration.

From these results, the peeling phenomenon is relevant to the adhesionproperty depending on various factors and had a close relationespecially with the internal stress and in the case of using the secondmaterial layer having a compressive stress and the first material layerhaving a tensile stress after heating treatment, the peeled off layer isfound peeled in the entire surface off a substrate. Further, in the casethe stress is changed by heating treatment or laser beam radiatingtreatment, it is preferable to use a material for the first materiallayer which had a tensile force value increased as compared with thatbefore heating treatment or laser beam radiating treatment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are views illustrating the embodiment 1.

FIGS. 2A to 2C are views illustrating the embodiment 2.

FIGS. 3A to 3D are views illustrating an experiment.

FIGS. 4A to 4C are views illustrating the embodiment 3.

FIGS. 5A to 5C are views illustrating the embodiment 4.

FIGS. 6A to 6D are views illustrating the steps of fabrication of anactive matrix substrate.

FIGS. 7A to 7C are views illustrating the steps of fabrication of anactive matrix substrate.

FIG. 8 is a view illustrating an active matrix substrate.

FIGS. 9A to 9D are views illustrating Example 2.

FIGS. 10A to 10E are views illustrating Example 3.

FIG. 11 is a view illustrating Example 4.

FIG. 12 is a view illustrating Example 5.

FIGS. 13A to 13D are views illustrating Example 6.

FIGS. 14A to 14C are views illustrating Example 7.

FIGS. 15A and 15B are view illustrating Example 8.

FIG. 16 is a view illustrating Example 8.

FIG. 17 is a view illustrating Example 9.

FIGS. 18A to 18F are views illustrating examples of electronicappliances.

FIGS. 19A to 19C are views illustrating examples of electronicappliances.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, embodiments of the invention will be described.

Embodiment 1

Hereinafter, typical peeling procedures of the invention will bedescribed concisely with reference to FIG. 1

In FIG. 1A, the reference numeral 10 denotes a substrate, 11 denotes afirst material layer having a tensile stress, 12 denotes a materiallayer having a compressive stress, and 13 denotes a peeled off layer.

In FIG. 1A, the substrate 10 may be a quartz substrate, a ceramicsubstrate or the like. Further, a silicon substrate, a metal substrate,or a stainless steel substrate may be used.

At first, as illustrated in FIG. 1A, the first material layer 11 isformed on the substrate 10. The first material layer 11 may have atensile stress even if it has a compressive stress immediately afterfilm formation and it is important for the layer to use a materialcausing no abnormality such as peeling by heating treatment or laserbeam radiating treatment in the peeled off layer formation and having atensile stress in a range of 1 to 1×10¹⁰ (Dyne/cm²) after the peeled offlayer formation. Typical examples are monolayers of elements selectedfrom W, WN, TiN, TiIs well as alloy materials and compounds containingthe foregoing elements as main components and their layered structure.

Next, the second material layer 12 is formed on the first material layer11. It is important for the second material layer 12 to use a materialcausing no abnormality such as peeling by heating treatment or laserbeam radiating treatment in the peeled off layer formation and having acompressive stress in a range of 1 to 1×10¹⁰ (Dyne/cm²) after the peeledoff layer formation. Typical examples of the second material layer 12are monolayers of silicon oxide, silicon nitride oxide, and metal oxidematerials and their layered structure. The second material layer 12 maybe formed by employing any film formation method such as a sputteringmethod, a plasma CVD method, a coating method and the like.

In this invention, it is important to make the second material layer 12has a compressive stress and the first material layer 11 has a tensilestress. The film thickness of the respective films may properly be setwithin a range of 1 nm to 1,000 nm so as to adjust the internal stressin the first material layer 11 and the internal stress in the secondmaterial layer 12. Further, heating treatment and laser beam radiatingtreatment may be carried out so as to adjust the internal stress in thefirst material layer 11 and the internal stress in the second materiallayer 12.

Further, in FIG. 1, although, for simplification of the process, anexample where the first material layer 11 is formed adjacently to thesubstrate 10 is illustrated, an insulating layer or a metal layer, whichwill become a buffer layer, may be formed between the substrate 10 andthe first material layer 11 to improve the adhesion property to thesubstrate 10.

Next, a peeled off layer 13 is formed on the second material layer 12(FIG. 1A). The peeled off layer 13 may be a layer containing a varietyof elements such as TFT (a thin film diode, an photoelectric conversionelement having a PIN junction of silicon, and a silicon resistorelement). Heating treatment to the extent that the substrate 10 canstand may be carried out. In this invention, even if the internal stressof the second material layer 12 and the internal stress of the firstmaterial layer 11 differ from each other, no peeling takes place by theheating treatment in the step of formation of the peeled off layer 13.

Next, the substrate 10 on which the first material layer 11 is formed ispeeled off by physical means (FIG. 1B). Since the second material layer12 has a tensile stress and the first material layer 11 has acompressive stress, peeling can be carried out with relatively slightforce. In this case, the example where the peeled off layer 13 isassumed to have a sufficient mechanical strength is exemplified, howeverin the case where the mechanical strength of the peeled off layer 13 isinsufficient, it is preferable to carry out peeling after a supportingbody (not illustrated) for fixing the peeled off layer 13 is stuck.

In such a manner, the peeled off layer 13 formed on the second materiallayer 12 can be separated from the substrate 10. The state after peelingis shown in FIG. 1C.

Further, after peeling, the peeled object, the peeled off layer 13, maybe stuck to a transfer body (not illustrated).

The invention can be applied to manufacturing methods of a variety ofsemiconductor devices. Especially, using plastic substrates for thetransfer body and the supporting body, weight is made light.

In the case of fabricating a liquid crystal display apparatus, thesupporting body is used as a counter substrate and a seal material as anadhesive to stick the supporting body to the peeled off layer. In thiscase, the element formed in the peeled off layer has a pixel electrodeand a liquid crystal material is packed between the pixel electrode andthe foregoing counter electrode. Further, the procedure of thefabrication of the liquid crystal display apparatus is not particularlylimited and may be carried out in a manner that after the countersubstrate as the supporting body is stuck and a liquid crystal isinjected, the substrate is peeled off and a plastic substrate as thetransfer body is stuck or after the pixel electrode is formed, thesubstrate is peeled and then the plastic substrate as a first transferbody is stuck and successively a counter substrate as a second transferbody is stuck.

In the case of fabricating a light emitting apparatus such as an ELlight emitting device, it is preferable to use a seal material for asupporting body to completely shut the light emitting element out of theoutside in a manner that outside substances such as water and oxygenwhich accelerate deterioration of an organic compound layer areprevented from penetration. Further, in the case of fabricating a lightemitting apparatus such as an EL light emitting device, it is preferablenot only for the supporting body but also for the transfer body, toprevent sufficiently outside substances such as water and oxygen whichaccelerate deterioration of an organic compound layer from penetration.The procedure of fabrication of the light emitting apparatus is notparticularly limited, and may be carried out in a manner that after alight emitting element is formed, a plastic substrate as the supportingbody is stuck and the substrate is peeled off. And then, a plasticsubstrate as the transfer body is stuck or after the light emittingelement is formed, the substrate is peeled and then the plasticsubstrate as a first transfer body is stuck and successively a countersubstrate as a second transfer body is stuck.

Embodiment 2

In this embodiment, the peeling procedure for peeling a substrate whilepreventing diffusion of impurities from a first material layer and thesubstrate after an underlying insulating layer is formed adjacently to apeeled off layer will concisely be described with reference to FIG. 2.

In FIG. 2A, the reference numeral 20 denotes a substrate, 21 denotes afirst material layer having a tensile stress, 22 denotes a secondmaterial layer having a compressive stress, 23 a and 23 b each denote anunderlying insulating layer, and 24 denotes a peeled off layer.

In FIG. 2A, the substrate 20 may be a glass substrate, a quartzsubstrate, a ceramic substrate or the like. Further, a siliconsubstrate, a metal substrate, or a stainless steel substrate may beused.

At first, as illustrated in FIG. 2A, the first material layer 21 isformed on the substrate 20. The first material layer 21 may have acompressive stress or a tensile stress immediately after film formationand it is important for the layer to use a material causing noabnormality such as peeling by heating treatment or laser beam radiatingtreatment in the peeled off layer formation and having a tensile stressin a range of 1 to 1×10¹⁰ (Dyne/cm²) after the peeled off layerformation. Typical examples are monolayers of elements selected from W,WN, TiN, TiIs well as alloy materials and compound materials containingthe foregoing elements as main components and their layered structure.

Next, the second material layer 22 is formed on the first material layer21. It is important for the second material layer 22 to use a materialcausing no abnormality such as peeling by heating treatment or laserbeam radiating treatment in the peeled off layer formation and having acompressive stress in a range of 1 to 1×10¹⁰ (Dyne/cm²) after the peeledoff layer formation. Typical examples of the second material layer 22are silicon oxide, silicon nitride oxide, and metal oxide materials andtheir layered structure. The second material layer 22 may be formed byemploying any film formation method such as a sputtering method, aplasma CVD method, a coating method and the like.

In this invention, it is important to make the second material layer 22have a compressive stress and the first material layer 21 have a tensilestress. The film thickness of the respective films may properly be setwithin a range of 1 nm to 1,000 nm so as to adjust the internal stressin the first material layer 21 and the internal stress in the secondmaterial layer 22. Further, heating treatment and laser beam radiatingtreatment may be carried out so as to adjust the internal stress in thefirst material layer 21 and the internal stress in the second materiallayer 22.

Further, in FIG. 2, although, for simplification of the process, anexample where the first material layer 21 is formed adjacently to thesubstrate 20 is illustrated, an insulating layer or a metal layer, whichwill become a buffer layer, may be formed between the substrate 20 andthe first material layer 21 to improve the adhesion property to thesubstrate 20.

Then, underlying insulating layers 23 a and 23 b are formed on thesecond material layer 22. In this case, a silicon nitride oxide film 23a (composition ratio Si=32%, O=27%, N=24%, and H=17%) with a thicknessof 50 nm (preferably 10 to 200 nm) is formed using raw material gases ofSiH₄, NH₃, and N₂O at a film formation temperature of 400° C. by aplasma CVD method and further a silicon nitride oxide film 23 b(composition ratio Si=32%, O=59%, N=7%, and H=2%) with a thickness of100 nm (preferably 50 to 200 nm) is layered thereon using raw materialgases of SiH₄ and N₂O at a film formation temperature of 400° C. by aplasma CVD method, however the layers are not limited to that and mayhave a monolayer structure or a layered structure of 3 or more layers.

Next, a peeled off layer 24 is formed on the underlying insulating layer23 b (FIG. 2A).

In the case of such a two-layered structure of the underlying insulatinglayers 23 a, 23 b, in the process of formation of the peeled off layer24, diffusion of impurities from the first material layer 21, the secondmaterial layer 22, and the substrate 20 can be prevented. Further, owingto the underlying insulating layers 23 a, 23 b, the adhesion propertybetween the second material layer 22 and the peeled off layer 24 can beimproved.

Further in the case the surface of the first material layer 21 or thesecond material layer 22 is roughened, the surface may be leveled beforeor after the formation of the underlying insulating layers. The coverageof the peeled off layer 24 becomes high by leveling, and therefore it ispreferable since the element characteristics are stabilized easily inthe case where the peeled off layer 24 containing an element is formed.Incidentally, as the leveling treatment, an etching back method forleveling by forming a coating film (a resist film or the like) and thencarrying out etching, a mechanochemical polishing method (CMP method),and the like may be employed.

Then, the substrate 20 bearing the first material layer 21 thereon ispeeled off by physical means (FIG. 2B). Since the second material layer22 has a compressive stress and the first material layer 21 has atensile stress, peeling can be carried out with a relatively slightforce. Further, in this case, the example where the peeled off layer 24is assumed to have a sufficient mechanical strength is exemplified,however in the case the mechanical strength of the peeled off layer 24is insufficient, it is preferable to carry out peeling after asupporting body (not illustrated) for fixing the peeled off layer 24 isstuck.

In such a manner, the peeled off layer 24 formed on the underlyinginsulating layer 22 can be separated from the substrate 20. The stateafter peeling is shown in FIG. 2C.

Further, after peeling, the peeled off layer 24 may be stuck to atransfer body (not illustrated).

The invention can be applied to manufacturing methods of a variety ofsemiconductor devices. Especially, using plastic substrates for thetransfer body and the supporting body, weight is made light.

In the case of fabricating a liquid crystal display apparatus, thesupporting body is used as a counter substrate and a seal material as anadhesive to stick the supporting body to the peeled off layer. In thiscase, the element formed in the peeled off layer has a pixel electrodeand a liquid crystal material is packed between the pixel electrode andthe foregoing counter electrode. Further, the procedure of thefabrication of the liquid crystal display apparatus is not particularlylimited and may be carried out in a manner that after the countersubstrate as the supporting body is stuck and a liquid crystal isinjected, the substrate is peeled off and a plastic substrate as thetransfer body is stuck or after the pixel electrode is formed, thesubstrate is peeled and then the plastic substrate as a first transferbody is stuck and successively a counter substrate as a second transferbody is stuck.

In the case of fabricating a light emitting apparatus such as an ELlight emitting device, it is preferable to use a supporting body as aseal material to completely shut the light emitting element out of theoutside so as to prevent outside substances such as water and oxygenwhich accelerate deterioration of an organic compound layer frompenetration. Further, in the case of fabricating a light emittingapparatus such as an EL light emitting device, it is preferable not onlyfor the supporting body but also the transfer body to sufficientlyprevent outside substances such as water and oxygen which acceleratedeterioration of an organic compound layer from penetration. Theprocedure of fabrication of the light emitting apparatus is notparticularly limited and may be carried out in a manner that after alight emitting element is formed, a plastic substrate as the supportingbody is stuck and the substrate is peeled off and a plastic substrate asthe transfer body is stuck or after the light emitting element isformed, the substrate is peeled and then the plastic substrate as afirst transfer body is stuck and successively a plastic substrate as asecond transfer body is stuck.

Embodiment 3

In this embodiment, in addition to the embodiment 1, an example wherelaser beam radiating or heating treatment is carried out in order topromote peeling will be described with reference to FIG. 4.

In FIG. 4A, the reference numeral 40 denotes a substrate, 41 denotes afirst material layer, 42 denotes a second material layer, and 43 denotesa peeled off layer.

Since the process to form up to the peeled off layer 43 is same as thatin the embodiment 1, the description will be omitted.

After the peeled off layer 43 is formed, laser beam radiation is carriedout (FIG. 3A). Laser beam to be employed includes gas laser such asexcimer laser, solid laser of YVO₄ laser, YAG laser, and semiconductorlaser. The state of laser oscillation may be both continuous oscillationand pulsed oscillation and the shape of the laser beam is alsooptionally linear, rectangular, circular, or elliptical. The wavelengthto be employed may be fundamental, second higher harmonics, or thirdhigher harmonics. Further, the scanning method may be carried out in thevertical direction, the transverse direction, or diagonal direction andfurther reciprocated.

As for the material as the first material layer 41, preferably amaterial capable of easily absorbing laser beam and a metal material isused, and a metal nitride material such as titanium nitride ispreferable. Incidentally, in order to transmit laser beam, a substratehaving translucency is employed for the substrate 40.

Next, the substrate 40 bearing the first material layer 41 thereon ispeeled off by physical means (FIG. 4B). Since the second material layer42 has a compressive stress and the first material layer 41 has atensile stress, peeling can be carried out with a relatively slightforce.

Laser beam radiation heats the first material layer 41 and the secondmaterial layer 42 to change the internal stress of both layers andpromote the peeling to make the peeling easy with slight force. Further,in this case, an example where the peeled off layer 43 is assumed tohave a sufficient mechanical strength is exemplified, however in thecase the mechanical strength of the peeled off layer 43 is insufficient,it is preferable to carry out peeling after a supporting body (notillustrated) for fixing the peeled off layer 43 is stuck.

In such a manner, the peeled off layer 43 formed on the second materiallayer 42 can be separated from the substrate 40. The state after thepeeling is illustrated in FIG. 4C.

Further, not being limited to laser beam, visible light rays, infraredrays, ultraviolet rays, microwave from halogen lamps or the like can beemployed.

Further, in place of the laser beam, heating treatment in an electricfurnace may be employed.

Further, before the adhesion of the supporting body or before theforegoing peeling by the physical means, heating treatment or laser beamradiating treatment may be carried out.

This embodiment may be combined with the embodiment 2.

Embodiment 4

In this embodiment, in addition to the embodiment 1, an example where agranular oxide is formed in the interface between a first material layerand a second material layer in order to promote peeling will bedescribed with reference to FIG. 5.

In FIG. 5A, the reference numeral 50 denotes a substrate, 51 denotes afirst material layer, 52 a denotes the granular oxide, 52 b denotes asecond material layer, and 53 denotes a peeled off layer.

Since the process to form up to the first material layer 51 is same asthat in the embodiment 1, the description will be omitted.

After the first material layer 51 is formed, the granular oxide 52 a isformed. As the granular oxide 52 a, a metal oxide material such as ITO(indium oxide-tin oxide alloy), an indium oxide-zinc oxide alloy(In₂O₃—ZnO), zinc oxide (ZnO) and the like may be used.

Next, while covering the granular oxide 52 a, the second material layer52 b is formed. As the second material layer 52 b, for example, siliconoxide, silicon nitride oxide, and metal oxide materials may be used.Incidentally, the second material layer 52 b may be formed by a filmformation method such as a sputtering method, a plasma CVD method, acoating method, and the like.

Next, the peeled off layer 53 is formed on the second material layer 52b (FIG. 5A).

Next, the substrate 50 bearing the first material layer 51 thereon ispeeled off by physical means (FIG. 5B). Since the second material layer52 b has a compressive stress and the first material layer 51 has atensile stress, peeling can be carried out with relatively slight force.

Formation of the granular oxide 52 a weakens the bonding force of thefirst material layer 51 and the second material layer 52 and changes themutual adhesion property to promote the peeling and make the peelingpossible with slight force. Further, in this case, the example where thepeeled off layer 53 is assumed to have a sufficient mechanical strengthis exemplified, however in the case the mechanical strength of thepeeled off layer 53 is insufficient, it is preferable to carry outpeeling after a supporting body (not illustrated) for fixing the peeledoff layer 53 is stuck.

In such a manner, the peeled off layer 53 formed on the second materiallayer 52 b can be separated from the substrate 50. The state afterpeeling is shown in FIG. 5C.

This embodiment may be combined with the embodiment 2 or the embodiment3.

The present invention with the above-described constitutions will bedescribed further in details along with examples as follows.

EXAMPLES Example 1

Examples of the invention will be described with reference to FIG. 6 toFIG. 8. Here, a method for simultaneously fabricating pixel portion andTFT (n-channel type TFT and p-channel type TFT) of driving circuitsformed in the vicinity of the pixel portion on a single substrate willbe described in details.

At first, on a substrate 100 a first material layer 101, a secondmaterial layer 102, and an underlying insulating layer 103 are formed toobtain a semiconductor film having a crystalline structure and thensubjected to etching treatment in a desired shape to form semiconductorlayers 104 to 108 separated like islands.

A glass substrate (#1737) is used as the substrate 100.

Further, as the first material layer 101, any material can be employedwithout particular restrictions if it has a tensile stress in a range of1 to ×10¹⁰ (Dyne/cm²) immediately before the peeling step to be carriedout later and a monolayer of any one of a metal material (Ti, Al, Ta, W,Mo, Cu, Cr, Nd, Fe, Ni, Co, Zr, Zn, Ru, Rh, Pd, Os, Ir, Pt and thelike), a semiconductor material (e.g. Si, Ge and the like), aninsulating material, and an organic material or their laminated layermay be employed. In this case, a titanium nitride film with a filmthickness of 100 nm by a sputtering method is used.

Further, as the second material layer 102, any material can be employedwithout particular restrictions if it has a compressive stress in arange of −1 to −1×10¹⁰ (Dyne/cm² immediately before the peeling step tobe carried out later and a monolayer of any one of a metal material (Ti,Al, Ta, W, Mo, Cu, Cr, Nd, Fe, Ni, Co, Zr, Zn, Ru, Rh, Pd, Os, Ir, Ptand the like), a semiconductor material (e.g. Si, Ge and the like), aninsulating material, and an organic material or their laminated layermay be employed. A monolayer or a laminated layer of a silicon oxidematerial or a metal oxide material may be employed. The bonding forcebetween the first material layer 101 and the second material layer 102is durable to heating treatment and it does not cause film peeling(referred also as to peeling). However, it is easy to carry out peelingin the interlayer or interface of the second material layer by physicalmeans.

And, As the underlying insulating film 103, a silicon oxynitride film103 a formed from SiH₄, NH₃, and N₂O as material gases (compositionratio: Si=32%, O=27%, N=24%, H=17%) is formed with a thickness of 50 nm(preferably 10 to 200 nm) and at a film formation temperature of 400° C.by using plasma CVD. Then, after the surface is cleaned with ozonewater, an oxide film on the surface is removed by means of dilutehydrofluoric acid (dilution with 1/100). Next, a silicon oxynitride film103 b formed from SiH₄ and N₂O as material gases (composition ratio:Si=32%, O=59%, N=7%, H=2%) is formed thereon with a thickness of 100 nm(preferably 50 to 200 nm) and at a film formation temperature of 400° C.by using plasma CVD to thereby form a lamination. Further, withoutexposure to an atmosphere, a semiconductor film having an amorphousstructure (in this case, amorphous silicon film) is formed to have athickness of 54 nm (preferably 25 to 80 nm) with SiH₄ as a filmformation gas and at a film formation temperature of 300° C. by usingplasma CVD.

In this example, the underlying insulting film 103 is shown in a form ofa two-layer structure, but a single layer of the insulating film or astructure in which two or more layers thereof are laminated may beadopted. Further, there is no limitation on the material of thesemiconductor film. However, the semiconductor film may be preferablyformed of silicon or silicon germanium (Si_(X)Ge_(1−X) (X=0.0001 to0.02)) alloy by using a known means (sputtering, LPCVD, plasma CVD, orthe like). Further, a plasma CVD apparatus may be a single wafer typeone or a batch type one. In addition, the underlying insulating film andthe semiconductor film may be continuously formed in the same filmformation chamber without exposure to an atmosphere.

And, after the surface of the semiconductor film having an amorphousstructure is cleaned, an extremely thin oxide film with a thickness ofabout 2 nm is formed from ozone water on the surface. Then, in order tocontrol a threshold value of a TFT, doping of a minute amount ofimpurity element (boron or phosphorous) is performed. Here, an iondoping method is used in which diborane (B₂H₆) is plasma-excited withoutmass-separation, and boron is added to the amorphous silicon film underthe doping conditions: an acceleration voltage of 15 kV; a gas flow rateof diborane diluted to 1% with hydrogen of 30 sccm; and a dosage of2×10¹²/cm².

Then, a nickel acetate salt solution containing nickel of 10 ppm inweight is applied using a spinner. Instead of the application, a methodof spraying nickel elements to the entire surface by sputtering may alsobe used.

Then, a heat treatment is conducted to perform crystallization, therebyforming a semiconductor film having a crystalline structure. A heatingprocess using an electric furnace or irradiation of strong light may beconducted for this heat treatment. In case of the heating process usingan electric furnace, it may be conducted at 500 to 650° C. for 4 to 24hours. Here, after the heating process (500° C. for 1 hour) fordehydrogenation is conducted, the heating process (at 550° C. for 4hours) for crystallization is conducted, thereby obtaining a siliconfilm having a crystalline structure. Note that, although crystallizationis performed by using the heating process using a furnace,crystallization may be performed by means of a lamp annealing apparatus.Also note that, although a crystallization technique using nickel as ametal element that promotes crystallization of silicon is used here,other known crystallization techniques, for example, a solid-phasegrowth method and a laser crystallization method, may be used.

Next, after the oxide film on the surface of the silicon film having acrystalline structure is removed by dilute hydrofluoric acid or thelike, irradiation of a first laser light (XeCl: wavelength of 308 nm)for raising a crystallization rate and repairing defects remaining incrystal grains is performed in an atmosphere or in an oxygen atmosphere.Excimer laser light with a wavelength of 400 nm or less, or the secondharmonic wave or the third harmonic wave of a YAG laser is used for thelaser light. In any case, pulse laser light with a repetition frequencyof approximately 10 to 1000 Hz is used, the pulse laser light iscondensed to 100 to 500 mJ/cm² by an optical system, and irradiation isperformed with an overlap ratio of 90 to 95%, whereby the silicon filmsurface may be scanned. Here, the irradiation of the first laser lightis performed in an atmosphere with a repetition frequency of 30 Hz andenergy density of 393 mJ/cm². Note that an oxide film is formed on thesurface by the first laser light irradiation since the irradiation isconducted in the atmosphere or in an oxygen atmosphere.

Next, after the oxide film formed by the first light irradiation isremoved by dilute hydrofluoric acid, a second laser light irradiation isperformed in a nitrogen atmosphere or in a vacuum, thereby leveling thesemiconductor film surface. Excimer laser light with a wavelength of 400nm or less, or the second harmonic wave or the third harmonic wave of aYAG laser is used as the laser light (the second laser light). Theenergy density of the second laser light is made larger than that of thefirst laser light, preferably made larger by 30 to 60 mJ/cm². Here, thesecond laser light irradiation is performed with a repetition frequencyof 30 Hz and energy density of 453 mJ/cm² to thereby set a P-V value(Peak to Valley, means the difference between the maximum value andminimum value) of unevenness in the semiconductor film surface to 50 nmor less. The P-V value can be obtained from AFM (Atomic ForceMicroscope).

Further, although the second laser light irradiation is conducted overthe surface in this example, a step of selectively performingirradiation at least on a pixel portion may be adopted since thereduction of an off current particularly has an effect on a TFT of thepixel portion.

Next, the surface is processed with ozone water for 120 seconds, therebyforming a barrier layer comprised of an oxide film with a thickness of 1to 5 nm in total.

Then, an amorphous silicon film containing an argon element, whichbecomes a gettering site, is formed on the barrier layer to have athickness of 150 nm by sputtering. The film formation conditions withsputtering in this example are: a film formation pressure of 0.3 Pa; agas (Ar) flow rate of 50 sccm; a film formation power of 3 kW; and asubstrate temperature of 150° C. Note that under the above conditions,the atomic concentration of the argon element contained in the amorphoussilicon film is 3×10²⁰/cm³ to 6×10²⁰/cm³, and the atomic concentrationof oxygen is 1×10¹⁹/cm³ to 3×10¹⁹/cm³. Thereafter, heat treatment at650° C. for 3 minutes is conducted using the lamp annealing apparatus toperform gettering.

Next, the amorphous silicon film containing the argon element, which isthe gettering site, is selectively removed with the barrier layer as anetching stopper, and then, the barrier layer is selectively removed bydilute hydrofluoric acid. Note that there is a tendency that nickel islikely to move to a region with a high oxygen concentration ingettering, and thus, it is desirable that the barrier layer comprised ofthe oxide film is removed after gettering.

Then, after a thin oxide film is formed from ozone water on the surfaceof the obtained silicon film having a crystalline structure (alsoreferred to as polysilicon film), a mask made of resist is formed, andan etching process is conducted thereto to obtain a desired shape,thereby forming the island-like semiconductor layers 104 to 108separated from one another. After the formation of the semiconductorlayers, the mask made of resist is removed.

Then, the oxide film is removed with the etchant containing hydrofluoricacid, and at the same time, the surface of the silicon film is cleaned.Thereafter, an insulating film containing silicon as its mainconstituent, which becomes a gate insulating film 109, is formed. Inthis example, a silicon oxynitride film (composition ratio: Si=32%,O=59%, N=7%, H=2%) is formed with a thickness of 115 nm by plasma CVD.

Next, as shown in FIG. 6A, on the gate insulating film 109, the firstconductive film 110 a with a thickness of 20 to 100 nm and the secondconductive film 110 b with a thickness of 100 to 400 nm are formed inlamination. In this example, a 50 nm thick tantalum nitride film and a370 nm thick tungsten film are sequentially laminated on the gateinsulating film 109.

As a conductive material for forming the first conductive film and thesecond conductive film, an element selected from the group consisting ofTa, W, Ti, Mo, Al and Cu, or an alloy material or compound materialcontaining the above element as its main constituent is employed.Further, a semiconductor film typified by a polycrystalline silicon filmdoped with an impurity element such as phosphorous, or an AgPdCu alloymay be used as the first conductive film and the second conductive film.Further, the present invention is not limited to a two-layer structure.For example, a three-layer structure may be adopted in which a 50 nmthick tungsten film, an alloy film of aluminum and silicon (Al—Si) witha thickness of 500 nm, and a 30 nm thick titanium nitride film aresequentially laminated. Moreover, in case of a three-layer structure,tungsten nitride may be used in place of tungsten of the firstconductive film, an alloy film of aluminum and titanium (Al—Ti) may beused in place of the alloy film of aluminum and silicon (Al—Si) of thesecond conductive film, and a titanium film may be used in place of thetitanium nitride film of the third conductive film. In addition, asingle layer structure may also be adopted.

Next, as shown in FIG. 6B, masks 112 to 117 are formed by an exposurestep, and the first etching process for forming gate electrodes andwirings is performed. The first etching process is performed with thefirst and the second etching conditions. An ICP (inductively coupledplasma) etching method maybe preferably used for the etching process.The ICP etching method is used, and the etching conditions (an electricenergy applied to a coil-shape electrode, an electric energy applied toan electrode on a substrate side, a temperature of the electrode on thesubstrate side, and the like) are appropriately adjusted, whereby a filmcan be etched to has a desired taper shape. Note that chlorine-basedgases typified by Cl₂, BCl₃, SiCl₄, and CCl₄, fluorine-based gasestypified by CF₄, SF₆, and NF₃, and O₂ can be appropriately used asetching gases.

In this example, RF (13.56 MHz) power of 150 W is applied also to thesubstrate (sample stage) to substantially apply a negative self-biasvoltage. Note that the size of electrode of the substrate is 12.5cm×12.5 cm, while the size of coil type of electrode (a quartz diskprovided by coil here) is 25 cm in the diameter. With the first etchingconditions, a W film is etched to form an end portion of the firstconductive layer into a tapered shape. Under the first etchingconditions, an etching rate to W is 200.39 nm/min, an etching rate toTaN is 80.32 nm/min, and a selection ratio of W to TaN is about 2.5.Further, with the first etching conditions, a taper angle of W isapproximately 26°. Thereafter, the first etching conditions are changedto the second etching conditions without removing the masks 110 to 115made of resist. CF₄ and Cl₂ are used as etching gases, the flow rate ofthe gases is set to 30/30 sccm, and RF (13.56 MHz) power of 500 W isapplied to a coil-shape electrode with a pressure of 1 Pa to generateplasma, thereby performing etching for about 30 seconds. RF (13.56 MHz)power of 20 W is also applied to the substrate side (sample stage) tosubstantially apply a negative self-bias voltage. Under the secondetching conditions in which CF₄ and Cl₂ are mixed, both the W film andthe TaN film are etched at the same level. With the second etchingconditions, an etching rate to W is 58.97 nm/min, and an etching rate toTaN is 66.43 nm/min. Note that an etching time may be increased by 10 to20% in order to conduct etching without remaining residue on the gateinsulating film.

In the first etching process as described above, the shape of the maskmade of resist is made appropriate, whereby the end portion of the firstconductive layer and the end portion of the second conductive layer eachhas a tapered shape due to the effect of the bias voltage applied to thesubstrate side. The angle of the tapered portion is sufficiently set to15 to 45°.

Thus, the first shape conductive layers 119 to 124 composed of the firstconductive layer and the second conductive layer (the first conductivelayers 119 a to 124 a and the second conductive layers 119 b to 124 b)are formed by the first etching process. The insulating film 109 thatbecomes the gate insulating film is etched by approximately 10 to 20 nm,and becomes a gate insulating film 118 in which regions which are notcovered by the first shape conductive layers 119 to 124 are thinned.

Next, the second etching process is conducted without removing the masksmade of resist. Here, SF₆, Cl₂ and O₂ are used as etching gases, theflow rate of the gases is set to 24/12/24 sccm, and RF (13.56 MHz) powerof 700 W is applied to a coil-shape electrode with a pressure of 1.3 Pato generate plasma, thereby performing etching for 25 seconds. RF (13.56MHz) power of 10 W is also applied to the substrate side (sample stage)to substantially apply a negative self-bias voltage. In the secondetching process, an etching rate to W is 227.3 nm/min, an etching rateto TaN is 32.1 nm/min, a selection ratio of W to TaN is 7.1, an etchingrate to SiON that is the insulating film 118 is 33.7 nm/min, and aselection ratio of W to SiON is 6.83. In the case where SF₆ is used asthe etching gas, the selection ratio with respect to the insulating film118 is high as described above. Thus, reduction in the film thicknesscan be suppressed. In this example, the film thickness of the insulatingfilm 118 is reduced by only about 8 nm.

By the second etching process, the taper angle of W becomes 70°. By thesecond etching process, the second conductive layers 126 b to 131 b areformed. On the other hand, the first conductive layers are hardly etchedto become the first conductive layers 126 a to 131 a. Note that thefirst conductive layers 126 a to 131 a have substantially the same sizeas the first conductive layers 119 a to 124 a. In actuality, the widthof the first conductive layer may be reduced by approximately 0.3 μm,namely, approximately 0.6 μm in the total line width in comparison withbefore the second etching process. However, there is almost no change insize of the first conductive layer.

Further, in the case where, instead of the two-layer structure, thethree-layer structure is adopted in which a 50 nm thick tungsten film,an alloy film of aluminum and silicon (Al—Si) with a thickness of 500nm, and a 30 nm thick titanium nitride film are sequentially laminated,under the first etching conditions of the first etching process inwhich: BCl₃, Cl₂ and O₂ are used as material gases; the flow rate of thegases is set to 65/10/5 (sccm); RF (13.56 MHz) power of 300 W is appliedto the substrate side (sample stage); and RF (13.56 MHz) power of 450 Wis applied to a coil-shape electrode with a pressure of 1.2 Pa togenerate plasma, etching is performed for 117 seconds. As to the secondetching conditions of the first etching process, CF₄, Cl₂ and O₂ areused, the flow rate of the gases is set to 25/25/10 sccm, RF (13.56 MHz)power of 20 W is also applied to the substrate side (sample stage); andRF (13.56 MHz) power of 500 W is applied to a coil-shape electrode witha pressure of 1 Pa to generate plasma. With the above conditions, it issufficient that etching is performed for about 30 seconds. In the secondetching process, BCl₃ and Cl₂ are used, the flow rate of the gases areset to 20/60 sccm, RF (13.56 MHz) power of 100 W is applied to thesubstrate side (sample stage), and RF (13.56 MHz) power of 600 W isapplied to a coil-shape electrode with a pressure of 1.2 Pa to generateplasma, thereby performing etching.

Next, the masks made of resist are removed, and then, the first dopingprocess is conducted to obtain the state of FIG. 6D. The doping processmay be conducted by ion doping or ion implantation. Ion doping isconducted with the conditions of a dosage of 1.5×10¹⁴ atoms/cm² and anaccelerating voltage of 60 to 100 keV. As an impurity element impartingn-type conductivity, phosphorous (P) or arsenic (As) is typically used.In this case, the first conductive layers and the second conductivelayers 126 to 130 become masks against the impurity element impartingn-type conductivity, and the first impurity regions 132 to 136 areformed in a self-aligning manner. The impurity element imparting n-typeconductivity is added to the first impurity regions 132 to 136 in aconcentration range of 1×10¹⁶ to 1×10¹⁷/cm³. Here, the region having thesame concentration range as the first impurity region is also called ann⁻⁻ region.

Note that although the first doping process is performed after theremoval of the masks made of resist in this example, the first dopingprocess may be performed without removing the masks made of resist.

Next, as shown in FIG. 7A, masks 137 to 139 made of resist are formed,and the second doping process is conducted. The mask 137 is a mask forprotecting a channel forming region and a periphery thereof of asemiconductor layer forming a p-channel TFT of a driver circuit, themask 138 is a mask for protecting a channel forming region and aperiphery thereof of a semiconductor layer forming one of n-channel TFTsof the driver circuit, and the mask 139 is a mask for protecting achannel forming region, a periphery thereof, and a storage capacitor ofa semiconductor layer forming a TFT of a pixel portion.

With the ion doping conditions in the second doping process: a dosage of1.5×10¹⁵ atoms/cm²; and an accelerating voltage of 60 to 100 keV,phosphorous (P) is doped. Here, impurity regions are formed in therespective semiconductor layers in a self-aligning manner with thesecond conductive layers 126 b to 128 b as masks. Of course, phosphorousis not added to the regions covered by the masks 137 to 139. Thus, thesecond impurity regions 140 to 142 and the third impurity region 144 areformed. The impurity element imparting n-type conductivity is added tothe second impurity regions 140 to 142 in a concentration range of1×10²⁰ to 1×10²¹/cm³. Here, the region having the same concentrationrange as the second impurity region is also called an n⁺ region.

Further, the third impurity region is formed at a lower concentrationthan that in the second impurity region by the first conductive layer,and is added with the impurity element imparting n-type conductivity ina concentration range of 1×10¹⁸ to 1×10¹⁹/cm³. Note that since doping isconducted by passing the portion of the first conductive layer having atapered shape, the third impurity region has a concentration gradient inwhich an impurity concentration increases toward the end portion of thetapered portion. Here, the region having the same concentration range asthe third impurity region is called an n⁻ region. Furthermore, theregions covered by the masks 138 and 139 are not added with the impurityelement in the second doping process, and become the first impurityregions 146 and 147.

Next, after the masks 137 to 139 made of resist are removed, masks 148to 150 made of resist are newly formed, and the third doping process isconducted as shown in FIG. 7B.

In the driver circuit, by the third doping process as described above,the fourth impurity regions 151, 152 and the fifth impurity regions 153,154 are formed in which an impurity element imparting p-typeconductivity is added to the semiconductor layer forming the p-channelTFT and to the semiconductor layer forming the storage capacitor.

Further, the impurity element imparting p-type conductivity is added tothe fourth impurity regions 151 and 152 in a concentration range of1×10²⁰ to 1×10²¹/cm³. Note that, in the fourth impurity regions 151,152, phosphorous (P) has been added in the preceding step (n⁻⁻ region),but the impurity element imparting p-type conductivity is added at aconcentration that is 1.5 to 3 times as high as that of phosphorous.Thus, the fourth impurity regions 151, 152 have a p-type conductivity.Here, the region having the same concentration range as the fourthimpurity region is also called a p⁺ region.

Further, the fifth impurity regions 153 and 154 are formed in regionsoverlapping the tapered portion of the second conductive layer 127 a,and are added with the impurity element imparting p-type conductivity ina concentration range of 1×10¹⁸ to 1×10²⁰/cm³. Here, the region havingthe same concentration range as the fifth impurity region is also calleda p⁻ region.

Through the above-described steps, the impurity regions having n-type orp-type conductivity are formed in the respective semiconductor layers.The conductive layers 126 to 129 become gate electrodes of a TFT.Further, the conductive layer 130 becomes one of electrodes, which formsthe storage capacitor in the pixel portion. Moreover, the conductivelayer 131 forms a source wiring in the pixel portion.

Next, an insulating film (not shown) that covers substantially theentire surface is formed. In this example, a 50 nm thick silicon oxidefilm is formed by plasma CVD. Of course, the insulating film is notlimited to a silicon oxide film, and other insulating films containingsilicon may be used in a single layer or a lamination structure.

Then, a step of activating the impurity element added to the respectivesemiconductor layers is conducted. In this activation step, a rapidthermal annealing (RTA) method using a lamp light source, a method ofirradiating light emitted from a YAG laser or excimer laser from theback surface, heat treatment using a furnace, or a combination thereofis employed.

Further, although an example in which the insulating film is formedbefore the activation is shown in this example, a step of forming theinsulating film may be conducted after the activation is conducted.

Next, the first interlayer insulating film 155 is formed of a siliconnitride film, and heat treatment (300 to 550° C. for 1 to 12 hours) isperformed, thereby conducting a step of hydrogenating the semiconductorlayers. (FIG. 7C) This step is a step of terminating dangling bonds ofthe semiconductor layers by hydrogen contained in the first interlayerinsulating film 155. The semiconductor layers can be hydrogenatedirrespective of the existence of an insulating film (not shown) formedof a silicon oxide film. Incidentally, in this example, a materialcontaining aluminum as its main constituent is used for the secondconductive layer, and thus, it is important to apply the heating processcondition that the second conductive layer can withstand in the step ofhydrogenation. As another means for hydrogenation, plasma hydrogenation(using hydrogen excited by plasma) may be conducted.

Next, the second interlayer insulating film 156 is formed from anorganic insulating material on the first interlayer insulating film 155.In this example, an acrylic resin film with a thickness of 1.6 μm isformed. Then, a contact hole that reaches the source wiring 131, contactholes that respectively reach the conductive layers 129 and 130, andcontact holes that reach the respective impurity regions are formed. Inthis example, a plurality of etching processes are sequentiallyperformed. In this example, the second interlayer insulting film isetched with the first interlayer insulating film as the etching stopper,the first interlayer insulating film is etched with the insulating film(not shown) as the etching stopper, and then, the insulating film (notshown) is etched.

Thereafter, wirings and pixel electrodes are formed by using Al, Ti, Mo,W and the like. As the material of the electrodes and pixel electrode,it is desirable to use a material excellent in reflecting property, suchas a film containing Al or Ag as its main constituent or a laminationfilm of the above film. Thus, source electrodes or drain electrodes 157to 162, a gate wiring 164, a connection wiring 163, and a pixelelectrode 165 are formed.

As described above, a driver circuit 206 having an n-channel TFT 201, ap-channel TFT 202, and an n-channel TFT 203 and a pixel portion 207having a pixel TFT 204 comprised of an n-channel TFT and a storagecapacitor 205 can be formed on the same substrate. (FIG. 8) In thisspecification, the above substrate is called an active matrix substratefor the sake of convenience.

In the pixel portion 207, the pixel TFT 204 (n-channel TFT) has achannel forming region 169, the first impurity region (n⁻⁻ region) 147formed outside the conductive layer 129 forming the gate electrode, andthe second impurity region (n⁺ region) 142 and 171 functioning as asource region or a drain region. Further, in the semiconductor layerfunctioning as one of the electrodes of the storage capacitor 205, thefourth impurity region 152 and the fifth impurity region 154 are formed.The storage capacitor 205 is constituted of the second electrode 130 andthe semiconductor layers 152, 154, and 170 with the insulating film (thesame film as the gate insulating film) 116 as dielectric.

Further, in the driver circuit 206, the n-channel TFT 201 (the firstn-channel TFT) has a channel forming region 166, the third impurityregion (n⁻ region) 144 that overlaps a part of the conductive layer 126forming the gate electrode through the insulating film, and the secondimpurity region (n⁺ region) 140 functioning as a source region or adrain region.

Further, in the driver circuit 206, the p-channel TFT 202 has a channelforming region 167, the fifth impurity region (p⁻ region) 153 thatoverlaps a part of the conductive layer 127 forming the gate electrodethrough the insulating film, and the fourth impurity region (p⁺ region)151 functioning as a source region or a drain region.

Furthermore, in the driver circuit 206, the n-channel TFT 203 (thesecond n-channel TFT) has a channel-forming region 168, the firstimpurity region (n⁻⁻ region) 146 outside the conductive layer 128forming the gate electrode, and the second impurity region (n⁺ region)141 functioning as a source region or a drain region.

The above TFTs 201 to 203 are appropriately combined to form a shiftregister circuit, a buffer circuit, a level shifter circuit, a latchcircuit and the like, thereby forming the driver circuit 206. Forexample, in the case where a CMOS circuit is formed, the n-channel TFT201 and the p-channel TFT 202 may be complementarily connected to eachother.

In particular, the structure of the n-channel TFT 203 is appropriate forthe buffer circuit having a high driving voltage with the purpose ofpreventing deterioration due to a hot carrier effect.

Moreover, the structure of the n-channel TFT 201, which is a GOLDstructure, is appropriate for the circuit in which the reliability takestop priority.

Further, the reliability can be improved by improving the flatness ofthe semiconductor film surface. Thus, in the TFT having the GOLDstructure, sufficient reliability can be obtained even if the area ofthe impurity region that overlaps the gate electrode through the gateinsulating film is reduced. Specifically, in the TFT having the GOLDstructure, sufficient reliability can be obtained even if the size ofthe portion that becomes the tapered portion of the gate electrode isreduced.

Further, In the TFT with the GOLD structure, a parasitic capacitanceincreases when the gate insulating film is thinned. However, the size ofthe tapered portion of the gate electrode (the first conductive layer)is reduced to reduce the parasitic capacitance, whereby the TFT becomesto enable high-speed operation with improved ‘f’ characteristic(Frequency characteristic) and to have sufficient reliability.

Note that, in the pixel TFT of the pixel portion 207 as well, the secondlaser light irradiation enables the reduction in off current and thereduction in fluctuation.

Further, an example of manufacturing the active matrix substrate forforming a reflection type display device is shown in this example.However, if the pixel electrode is formed of a transparent conductivefilm, a transmission type display device can be formed although thenumber of photomasks is increased by one.

Further, a glass substrate is used in this example; however, thesubstrate is not particularly limited to the glass one, quartz, asemiconductor, a ceramics and a metal one also can be used.

Furthermore, after obtain a state of FIG. 8, the substrate 100 can bepeeled off if the mechanical strength of a layer containing TFT (peeledoff layer) provided on the second material layer 102. The secondmaterial layer has a compression stress; and the first material has atensile stress, so that the substrate 100 can be peeled off in arelatively small power. Due to the mechanical strength of the peeled offlayer is insufficient, it is desirable to peel off after the peeled offlayer is pasted to a support stand which is for fixation.

Example 2

In this example, the steps of fabricating an active matrix type liquidcrystal display apparatus by peeling the substrate 100 from the activematrix substrate fabricated in Example 1 and sticking a plasticsubstrate will be described below. FIG. 9 will be used for thedescription.

In FIG. 9A, the reference numeral 400 denotes a substrate, 401 denotes afirst material layer, 402 denotes a second material layer, 403 denotesan underlying insulating layer, 404 a denotes an element of a drivingcircuit 413, 404 b denotes an element of a pixel portion 414, and 405denotes a pixel electrode. Here, the term element, means a semiconductorelement (typically TFT) to be employed as a switching element of apixel, MIM element or the like. The active matrix substrate illustratedin FIG. 9A is a simplified active matrix substrate illustrated in FIG. 8and the substrate 100 in FIG. 8 corresponds to the substrate 400 in FIG.9A. Similarly, 401 in FIG. 9A corresponds to 101 in FIG. 8, 402 in FIG.9A to 102 in FIG. 8, 403 in FIG. 9A to 103 in FIG. 8, 404 a in FIG. 9Ato 201 and 202 in FIG. 8, 404 b in FIG. 9A to 204 in FIG. 8, and 405 inFIG. 9A to 165 in FIG. 8, respectively.

At first, according to Example 1, after the active matrix substrate inthe state illustrated in FIG. 8 is obtained, an oriented film 406 a isformed on the active matrix substrate illustrated in FIG. 8 and rubbingtreatment is carried out. Incidentally, in this example, beforeformation of the oriented film, column-like spacers (not illustrated)for keeping a substrate gap are formed at desired positions bypatterning an organic resin film such as an acrylic resin film. In placeof the column-like spacers, spherical spacers may be applied to theentire face of the substrate.

Next, a counter substrate, which is to be a supporting body 407, is madeready. The counter substrate is equipped with a color filter (notillustrated) in which a coloring layer and a light shielding layer arearranged corresponding to respective pixels. A light shielding layer isalso formed in the portions of the driving circuits. A leveling film(not illustrated) covering the color filter and the light shieldinglayer is formed. Next, a counter electrode 408 of a transparent film isformed in the pixel portion on the leveling film and an oriented film406 b is formed on the entire face of the counter substrate and rubbingtreatment is carried out.

After that, the active matrix substrate 400 comprising the pixel portionand the driving circuits therein and the supporting body 407 are stuckto each other with a seal material, which becomes an adhesive layer 409.Filler is added to the seal material and owing to the filler and thecolumn-like spacers, two substrates are stuck to each other at an eveninterval. Next, a liquid crystal material 410 is injected between bothsubstrates and perfectly sealed by a sealing agent (not illustrated)(FIG. 9B). Any known liquid crystal material may be employed for theliquid crystal material 410.

Next, the substrate 400 on which the first material layer is formed ispeeled out (FIG. 9 c). Since the second material layer 402 hascompressive stress and the first material layer 401 has tensile stress,peeling can be carried out with a relatively slight force.

Next, the resulting body is stuck to a transfer body 412 through anadhesive layer 411 of epoxy resin or the like. In this example, thetransfer body 412 is to be a plastic substrate to make it lightweight.

In such a manner, a flexible and active matrix type liquid crystaldisplay apparatus is completed. If necessary, the flexible substrate 412or the counter substrate is cut into a desired shape. Further, apolarizing plate (not illustrated) is properly arranged by employing aknown technique. Also, FPC (not illustrated) is stuck by employing aknown technique.

Example 3

In Example 2, examples with steps that are attaching the countersubstrate as a supporting body, and then peeling off the substrate afterinjecting liquid crystals, finally sticking the plastic substrate as atransfer body, are described. In Example 3, examples that are, as shownin FIG. 8, after forming the active matrix substrate, peeling off thesubstrate, attaching a plastic substrate as a first transfer body and aplastic substrate as a second transfer body together, will be describedbelow. FIG. 10 will be used for the description.

In FIG. 10A, the reference numeral 500 denotes a substrate, 501 denotesa first material layer, 502 denotes a second material layer, 503 denotesan underlying insulating layer, 504 a denotes an element of a drivingcircuit 514, 504 b denotes an element of a pixel portion 515, and 505denotes a pixel electrode. The active matrix substrate illustrated inFIG. 10A is a simplified active matrix substrate illustrated in FIG. 8and the substrate 100 in FIG. 8 corresponds to the substrate 500 in FIG.10A. Similarly, 502 in FIG. 10A corresponds to 102 in FIG. 8, 503 inFIG. 10A to 103 in FIG. 8, 504 a in FIG. 10A to 201 and 202 in FIG. 8,504 b in FIG. 10A to 204 in FIG. 8, and 505 in FIG. 10A to 165 in FIG.8, respectively.

At first, according to Example 1, after the active matrix substrate inthe state illustrated in FIG. 8 is obtained, the substrate 500 on whichthe first material layer is formed is peeled out (FIG. 10 b). Since thesecond material layer 502 has compressive stress and the first materiallayer 501 has tensile stress, peeling can be carried out with arelatively slight force.

Next, the resulting body is stuck to a transfer body 507 (a firsttransfer body) through an adhesive layer 506 of epoxy resin or the like.In this example, the transfer body 507 is to be a plastic substrate tomake it lightweight. (FIG. 10 c)

Then, an alignment film 506 a is formed and rubbing treatment is carriedout. Incidentally, in this example, before formation of the alignmentfilm, column-like spacers (not illustrated) for keeping a substrate gapare formed at desired positions by patterning an organic resin film suchas an acrylic resin film. In place of the column-like spacers, sphericalspacers may be applied to the entire face of the substrate.

Next, a counter substrate, which is to be a supporting body 510, is madeready. The counter substrate is equipped with a color filter (notillustrated) in which a coloring layer and a light shielding layer arearranged corresponding to respective pixels. A light shielding layer isalso formed in the portions of the driving circuits. A leveling film(not illustrated) covering the color filter and the light shieldinglayer is formed. Next, a counter electrode 509 of a transparent film isformed in the pixel portion on the leveling film and an oriented film508 b is formed on the entire face of the counter substrate and rubbingtreatment is carried out.

After that, the plastic film substrate 507 connecting the pixel portionand the driving circuits therein and the supporting body 510 are stuckto each other with a seal material, which becomes an adhesive layer 512.(FIG. 10D) Filler is added to the seal material and owing to the fillerand the column-like spacers, two substrates are stuck to each other atan even interval. Next, a liquid crystal material 513 is injectedbetween both substrates and perfectly sealed by a sealing agent (notillustrated) (FIG. 10D). Any known liquid crystal material may beemployed for the liquid crystal material 513.

In such a manner, a flexible and active matrix type liquid crystaldisplay apparatus is completed. If necessary, the flexible substrate 507or the counter substrate is cut into a desired shape. Further, apolarizing plate (not illustrated) is properly arranged by employing aknown technique. Also, FPC (not illustrated) is stuck by employing aknown technique.

Example 4

The structure of the obtained liquid crystal module according to theExample 2 or 3, is described with the reference to the top of view ofFIG. 11. The substrate 507 according to the Example 2 or the substrate507 according to the Example 3 corresponds to a substrate 301.

A pixel portion 304 is placed in the center of the substrate 301. Asource single line driving circuit 302 for driving source signal linesis positioned above the pixel portion 304. Gate signal line drivingcircuits 303 for driving gate signal lines are placed to the left andright of the pixel portion 304. Although the gate signal line drivingcircuits 303 are symmetrical with respect to the pixel portion in thisexample, the liquid crystal module may have only one gate signal linedriving circuit on one side of the pixel portion. Of the above twooptions, a designer can choose the arrangement that suits betterconsidering the substrate size or the like of the liquid crystal module.However, the symmetrical arrangement of the gate signal line drivingcircuits shown in FIG. 11 is preferred in terms of circuit operationreliability, driving efficiency, and the like.

Signals are inputted to the driving circuits from flexible printedcircuits (FPC) 305. The FPCs 305 are press-fit through an anisotropicconductive film or the like after opening contact holes in theinterlayer insulating film and resin film and forming a connectionelectrode 309 so as to reach the wiring lines arranged in given placesof the substrate 301. The connection electrode is formed from ITO inthis example.

A sealing agent 307 is applied to the substrate along its perimetersurrounding the driving circuits and the pixel portion. An oppositesubstrate 306 is bonded to the substrate 301 by the sealing agent 307while a spacer 310 formed in advance on a film substrate keeps thedistance between the two substrates constant. A liquid crystal materialis injected through an area of the substrate that is not coated with thesealing agent 307. The substrates are then sealed by an end-sealingmaterial 308. The liquid crystal module is completed through the abovesteps.

Although all of the driving circuits are formed on the substrate in theexample shown here, several ICs may be used for some of the drivingcircuits.

This example can be implemented by freely combining with Example 1.

Example 5

Example 1 shows an exemplary reflection type display device in which apixel electrode is made of a metal material with reflectivity. In thisexample, an exemplary transmission type display device is shown, inwhich a pixel electrode is made of a conductive film with lighttransparency.

The processes up to the process of forming an interlayer insulating filmare the same as those in Example 1. Therefore, these processes will beomitted here. After the interlayer insulating film is formed inaccordance with Example 1, a pixel electrode 601 made of a conductivefilm with light transparency is formed. As the conductive film havinglight transparency, ITO (indium tin oxide alloy), an indium oxide-zincoxide alloy (In₂O₃—ZnO), zinc oxide (ZnO), or the like may be used.

Thereafter, contact holes are formed in the interlayer insulating film600. Then, connection electrodes 602 overlapping the pixel electrodesare formed. The connection electrodes 602 are connected to drain regionsthrough contact holes. Furthermore, a source region or a drain region ofanother TFT is also formed simultaneously with the connectionelectrodes.

Herein, an example in which all the driver circuits are formed on asubstrate is shown. However, several ICs may be used in a part of adriver circuit.

An active matrix substrate is formed as described above. Using theactive matrix substrate, after peel off the substrate, a film havingcompression stress (not shown) and a plastic substrate are attached toeach other, a liquid crystal module is manufactured in accordance withExamples 2 to 4, and a backlight 604 and a light-guiding plate 605 areprovided, followed by disposing a cover 606, whereby an active matrixtype liquid crystal display device as shown a part of a sectional viewin FIG. 12 is completed. The cover 606 and the liquid crystal module areattached to each other with an adhesive or an organic resin.Furthermore, the plastic substrate may be attached to a countersubstrate by filling an organic resin between a frame and a substrate soas to surround the frame. Since the apparatus is of a transmission type,polarizing plates 603 are attached to both the plastic substrate and thecounter substrate. This example can be freely combined with Examples 1to 4.

Example 6

In this example, an example of fabricating a light emitting apparatusequipped with EL (electro luminescence) elements formed on a plasticsubstrate will be described with the reference to FIG. 13.

In FIG. 13A, the reference numeral 700 denotes a substrate, 701 denotesa first material layer, 702 denotes a second material layer, 703 denotesan underlying insulating layer, 704 a denotes an element of a drivingcircuit 711, 704 b and 704 c denote elements of pixel portion 712, and705 denotes OLED (organic light emitting device). In this case, theterm, element, means a semiconductor element (typically TFT) to beemployed as a switching element of a pixel in the case of an activematrix type light emitting device or a MIM element, OLED or the like.Covering these elements, an interlayer insulating layer 706 is formed.The interlayer insulating layer 706 is preferable to have more flatsurface after film formation. Incidentally, the interlayer insulatinglayer 706 is not necessarily required to be formed.

According to any one of the embodiments 2 to 4, layers 701 to 703 may beformed on the substrate 700.

These elements (including 704 a, 704 b, and 704 c) may be formedaccording to the n-channel type TFT 201 of the above-described Example 1and the p-channel type TFT 202 of the above-described Example 1.

The OLED 705 comprises a layer (hereinafter, referred to as organiclight emitting layer) containing an organic compound (an organic lightemitting material) capable of providing electroluminescence generated byelectric field application, an anode layer, and a cathode layer. Theluminescence of organic compounds includes light emission (fluorescence)at the time of turning back to the basis state from the singletexcitation state and light emission (phosphorescence) at the time ofturning back to the basis state from the triplet excitation state andthe light emitting device of the invention may be based on either one ofthe light emission between both types of light emission or on both. Inthis specification, all of the layers formed between the anode and thecathode of the OLED are defined as an organic light emitting layer. Theorganic light emitting layer practically includes a light emittinglayer, a hole injection layer, an electron injection layer, a holetransportation layer, an electron transportation layer and the like.Basically, the OLED has a layered structure of an anode/a light emittinglayer/a cathode in this order and in addition to the structure, the OLEDmay have a layered structure of an anode/a hole injection layer/a lightemitting layer/a cathode, or an anode/a hole injection layer/a lightemitting layer/an electron transportation layer/a cathode in this order.

When the state illustrated in FIG. 13A is obtained by theabove-described method, the supporting body 708 is stuck by the adhesivelayer 707 (FIG. 13B). In this example, a plastic substrate is used asthe supporting body 708. Practically, as the supporting body, a resinsubstrate with a thickness of 10 μm or thicker, for example, PES(polyethylene sulfone), PC (polycarbonate), PET (polyethyleneterephthalate), or PEN (polyethylenenaphthalate)could be employed. Inthe case being positioned in the observer's side (the user side of thelight emitting device) in relation to the OLED, the supporting body 708and the adhesive layer 707 are required to be a light-transmissivematerial.

Next, the substrate 700 bearing the first material layer 701 thereon ispeeled off by physical means (FIG. 13C). Since the second material layer702 had a compressive stress and the first material layer 701 had atensile stress, peeling could be carried out with relatively slightforce.

Next, the resulting substrate is stuck to a transfer body 710 by anadhesive layer 709 of epoxy resin or the like (FIG. 13D). In thisexample, the transfer body 710 is a plastic film substrate to make theweight light.

In such a manner, a flexible light emitting device sandwiched between aflexible supporting body 708 and a flexible transfer body 710 isobtained. Incidentally, if the supporting body 708 and the transfer body710 are of a single material, the thermal expansion coefficient becomesequal and therefore, the device is made hard to be endurable to effectsof stress strain by temperature change.

If necessary, the flexible supporting body 708 or the flexible transferbody 710 is cut into a desired shape. Also, FPC (not illustrated) isstuck by employing a known technique.

Example 7

In Example 6, the examples with the steps that are, attaching thesupporting body, attaching a plastic substrate as a transfer body afterpeeling off the substrate, are described. In Example 7, an example offabrication an EL (light emitting display device having elements) by thesteps that are, peeling off the substrate, attaching a plastic substrateas a first transfer body and a plastic substrate as a second transferbody together, will be described. FIG. 14 will be used for thedescription.

In FIG. 14A, the reference numeral 800 denotes a substrate, 801 denotesa first material layer, 802 denotes a second material layer, 803 denotesan underlying insulating layer, 404 a denotes an element of a drivingcircuit 811, 804 b and 804 c denote elements of a pixel part 812, and805 denotes a OLED (Organic Light Emitting Device). In this case, theterm, element, means a semiconductor element (typically TFT) to beemployed as a switching element of a pixel in the case of an activematrix type light emitting device or a MIM element, OLED or the like. Aninterlayer insulting film 806 is formed to cover all these elements. Theinterlayer insulating layer 806 is preferable to have more flat surfaceafter film formation. Incidentally, the interlayer insulating layer 806is not necessarily required to be formed.

According to any one of the Examples 2 to 4, layers 801 to 803 may beformed on the substrate 700.

These elements (including 804 a, 804 b, 804 c) may be formed accordingto the n-channel type TFT 201 of the above-described Example 1 and thep-channel type TFT 202 of the above-described Example 1.

When the state illustrated in FIG. 14A is obtained by theabove-described method, the substrate 800 bearing the first materiallayer 801 thereon is peeled off by physical means (FIG. 14B). Since thesecond material layer 802 have a compressive stress and the firstmaterial layer 801 have a tensile stress, peeling could be carried outwith relatively slight force.

Next, the resulting substrate is stuck to a transfer body (the firsttransfer body) 810 by an adhesive layer 809 of epoxy resin or the like.In this example, the transfer body 810 is a plastic film substrate tomake the weight light.

Next, the resulting substrate is stuck to a base material (a secondtransfer body) by an adhesive layer 807. (FIG. 14C) In this example, theplastic substrate is used as the base material 808. Practically, as thetransfer body 810 and the base material 808, resin substrates with athickness of 10 μm or thicker, for example, PES (polyethylene sulfone),PC (polycarbonate), PET (polyethylene terephthalate), or PEN(polyethylene naphthalate) can be employed. In the case being positionedin the observer's side (the user side of the light emitting device) inrelation to the OLED, the base material 808 and the adhesive layer 807are required to be a light-transmissive material.

In such a manner, a flexible light emitting device sandwiched between aflexible base material 808 and a flexible transfer body 810 is obtained.Incidentally, if the base material 808 and the transfer body 810 are ofa single material, the thermal expansion coefficient become equal andtherefore, the device is made hard to be endurable to effects of stressstrain by temperature change.

If necessary, the flexible base material 808 or the flexible transferbody 810 is into a desired shape. Also, FPC (not illustrated) is stuckby employing a known technique.

Example 8

The structure of the obtained EL (Electro Luminescence) module accordingto Example 6 or 7 is described with the reference to the top of view ofFIG. 15. The transcript body 810 according to the example corresponds toa film substrate 900.

FIG. 15A is a top view of an EL module, and FIG. 15B is a sectional viewtaken along a line A—A′ of FIG. 15A. In FIG. 15A, on a film substrate900 having an flexibility (for example, a plastic substrate, or thelike), a film 901 having compression stress (for example a Oxidationsilicon film) is provided, and a pixel portion 902, a source side drivercircuit 904, and a gate side driver circuit 903 are formed thereon. Thepixel portion and the driver circuits can be obtained in accordance withthe above-described Example 1 or 2.

Further, reference numeral 918 indicates an organic resin, and referencenumeral 919 indicates a protective film. The pixel portion and thedriver circuit portions are covered by the organic resin 918, and theorganic resin is covered by the protective film 919. Further, theprotective film 919 is sealed by a cover member 920 using an adhesive.The cover member 920 is connected before peeling off as a support stand.It is desirable that the cover member 920 is made of the same materialas the substrate 900, for example, is a plastic substrate in order towithstand deformation due to heat or external force, and a materialprocessed to have the concave shape (with a depth of 3 to 10 μm) asshown in FIG. 15B is used for the cover member 920. Further, it isdesirable that the material is further processed to form a concaveportion (with a depth of 50 to 200 μm) into which a drying agent 921 canbe arranged. Further, in the case where multiple EL modules aremanufactured, after the substrate and the cover member are attached witheach other, segmentation may be conducted using a CO₂ laser or the likesuch that end surfaces match with each other.

Note that reference numeral 908 indicates a wiring for transmittingsignals input to the source side driver circuit 904 and the gate sidedriver circuit 903, and receives a video signal and a clock signal froman FPC (flexible printed circuit) 909 that is an external inputterminal. Note that although only the FPC is shown in the figure, aprinted wiring board (PWB) may be attached to the FPC. The lightemitting device in this specification includes not only the main body ofthe light emitting device but also the light emitting device attachedwith the FPC or PWB.

Next, the sectional structure is described with reference to FIG. 15B. Afilm 901 having thermal conductivity is formed on the film substrate900, and an insulating film 910 is provided thereon, the pixel portion902 and the gate side driver circuit 903 are formed above the insulatingfilm 910, and the pixel portion 902 is constituted of a plurality ofpixels including a current control TFT 911 and a pixel electrode 912electrically connected to a drain of the current control TFT 911.Further, the gate side driver circuit 903 is formed by using a CMOScircuit in which an n-channel TFT 913 and a p-channel TFT 914 arecombined.

The above TFTs (including 911, 913, and 914) may be manufactured inaccordance with the n-channel TFT and the p-channel TFT in Example 1.

Incidentally, after the pixel portion 902, the source side drivercircuit 904 and the gate side driver circuit 903 are formed on the samesubstrate in accordance with Example 1 and 2, further, according toEmbodiment mode, a support stand (here indicates a cover member) isconnected, a substrate (not shown) is peeled off thereafter, and thefilm substrate 900 is attached.

Further, in a case that the cover member 920 is made for a concave shapeas shown in FIG. 15B, after bonding the cover member 920 which becomes asupport stand, the part of a wiring lead-out terminal (part ofconnection) becomes only the insulating film 910, So that the mechanicalstrength becomes weak, therefore, it is desirable to attach the FPC 909before peeling off and to use a organic resin 922 for fixation.

Note that, as to a material of the insulating film provided between theTFT and the OLED, it is appropriate to use a material that not onlyblocks diffusion of impurity ions such as alkali metal ions oralkaline-earth metal ions but also positively adsorbs the impurity ionssuch as alkali metal ions or alkaline-earth metal ions, and further touse a material that can withstand a subsequent process temperature. Asthe material that satisfies the above conditions, a silicon nitride filmcontaining a large amount of fluorine is given as an example. Theconcentration of fluorine contained in the silicon nitride film is1×10¹⁹/cm³ or more, and preferably, the composition ratio of fluorine inthe silicon nitride film is 1 to 5%. Fluorine in the silicon nitridefilm bonds to alkali metal ions or alkaline-earth metal ions, and isadsorbed into the film. Further, as another example, there is given anorganic resin film containing particulates comprised of a stibium (Sb)compound, a stannum (Sn) compound or an indium (In) compound, whichadsorbs alkali metal ions, alkaline-earth metal ions or the like, forexample, an organic resin film containing particulates of stibiumpentoxide (Sb₂O₅. nH₂O). Note that this organic resin film containsparticulates with an average particle size of 10 to 20 nm, and has highlight transmission properties. The stibium compound typified by thestibium pentoxide particulates is likely to adsorb impurity ions such asalkali metal ions or alkaline-earth metal ions.

The pixel electrode 912 functions as a cathode of a light emittingelement (OLED). Further, banks 915 are formed at both ends of the pixelelectrode 912, and an organic compound layer 916 and an anode 917 of thelight emitting element are formed on the pixel electrode 912.

As to the organic compound layer 916, a light emitting layer, a chargetransportation layer and a charge injection layer may be freely combinedto form an organic compound layer (layer for light emission and movementof carrier for light emission). For example, a low molecular weightorganic compound material or a high molecular weight organic compoundmaterial may be used. Further, as the organic compound layer, a thinfilm formed from a light emitting material that emits light by singletexcitation (fluorescence) (singlet compound) or a thin film formed froma light emitting material that emits light by triplet excitation(phosphorescence) (triplet compound) can be used. Further, an inorganicmaterial such as silicon carbide can be used for the chargetransportation layer or the charge injection layer. Known materials canbe used for the organic EL materials or inorganic materials.

An anode 917 also functions as a wiring common to all the pixels, and iselectrically connected to the FPC 909 through the connection wiring 908.Further, all the elements contained in the pixel portion 902 and thegate side driver circuit 903 are covered by the anode 917, the organicresin 918 and the protective film 919.

Note that a material that is transparent or semitransparent to visiblelight is preferably used for the organic resin 918. Further, the organicresin 918 is desirably formed from a material that does not permeatemoisture or oxygen as much as possible.

Further, after the light emitting element is completely covered by theorganic resin 918, it is preferable that the protective film 919 isprovided at least on the surface (exposed surface) of the organic resin918 as shown in FIGS. 15. Further, the protective film may be providedon the entire surface including the back surface of the substrate. Here,it is necessary to note that the protective film is not deposited to theportion where the external input terminal (FPC) is provided. A mask maybe used in order not to form the protective film. Alternatively, theexternal input terminal portion may be covered by a tape formed ofTeflon (registered trademark) or the like, which is used as a maskingtape in a CVD apparatus, in order not to form the protective film.

The light emitting element is sealed by the protective film 919 with theabove-described structure, whereby the light emitting element can becompletely shut from the outside. Thus, it is possible to prevent asubstance that promotes deterioration due to oxidization of the organiccompound layer, such as moisture or oxygen from permeating from theoutside. Additionally, divergence from a film having thermalconductivity can be emitted. Therefore, the light emitting device withhigh reliability can be obtained.

Further, the structure may be adopted in which a pixel electrode is ananode, and an organic compound layer and a cathode are laminated tothereby provide light emission in an opposite direction to that in FIG.15. FIG. 16 shows an example thereof. Note that a top view of theexample is the same as that of FIG. 15, and thus is omitted.

A sectional structure shown in FIG. 16 is described below. An insulatingfilm 1010 is provided on a film substrate 1000, a pixel portion 1002 anda gate side driver circuit 1003 are formed above the insulating film1010, the pixel portion 1002 is constituted of a plurality of pixelsincluding a current control TFT 1011 and a pixel electrode 1012electrically connected to a drain of the current control TFT 1011. Notethat in accordance with Embodiment mode, after a peeled off layer formedon the substrate is peeled off, the film substrate 1000 is attached.Further, the gate side driver circuit 1003 is formed by using a CMOScircuit in which an n-channel TFT 1013 and a p-channel TFT 1014 arecombined.

These TFTs (including 1011, 1013, 1014) can be manufactured according tothe n-channel TFT 201, p-channel TFT 202 of the above Example 1.

The pixel electrode 1012 functions as an anode of a light emittingelement. Further, banks 1015 are formed at both ends of the pixelelectrode 1012, and an organic compound layer 1016 and an anode 1017 ofthe light emitting element are formed on the pixel electrode 1012.

The cathode 1017 also functions as a wiring common to all the pixels,and is electrically connected to an FPC 1009 via a connection wiring1008. Further, all the elements contained in the pixel portion 1002 andthe gate side driver circuit 1003 are covered by the cathode 1017, anorganic resin 1018 and a protective film 1019. Further, a cover member1020 is bonded by an adhesive. In addition, a concave portion isprovided in the cover member, and a drying agent 1021 is arrangedtherein.

Further, in a case that the cover member 1020 is made for a concaveshape as shown in FIG. 16, after bonding the cover member 1020 whichbecomes a support stand, the part of a wiring lead-out terminal (part ofconnection) becomes only the insulating film 1010, So that themechanical strength becomes weak, therefore, it is desirable to attachthe FPC 1009 before peeling off and to use an organic resin 922 forfixation.

Further, in FIG. 16, the pixel electrode is the anode, and the organiccompound layer and the cathode are laminated. Thus, the light emissiondirection is indicated by an arrow in FIG. 16.

Note that although a top gate TFT is described as an example in Example8, however, the present invention can be applied regardless of thestructure of TFT, a bottom gate (inverted stagger) TFT and a stagger TFTalso can be applied as examples.

Example 9

In Example 8, an example of using a top gate type TFT is exemplified,however it is also possible to use a bottom gate type TFT. Here anexample of using the bottom gate type TFT will be exemplified asillustrated in FIG. 17.

As illustrated in FIG. 17, all of an n-channel type TFT 1113, ap-channel type TFT 1114, and an n-channel type TFT 1111 are all made tohave a bottom gate structure. Their bottom gate structure could befabricated by known technique. Incidentally, active layers of these TFTmay be a semiconductor film (polysilicon or the like) having a crystalstructure or a semiconductor film (amorphous silicon or the like) havingan amorphous structure.

Further, in FIG. 17, the reference numeral 1100 denotes a flexible filmsubstrate (e.g., a plastic substrate or the like), 1101 denotes a filmhaving a compressive stress (e.g., a silicon oxide film), 1102 denotes apixel part, 1103 denotes a gate side driving circuit, 1110 denotes aninsulating film, 1112 denotes a pixel electrode (a cathode), 1115denotes a bank, 1116 denotes an organic compound layer, 1117 denotes ananode, 1118 denotes organic resin, 1119 denotes a protective film, 1120denotes a cover material, 1121 denotes a desiccating agent, and 1122denotes organic resin.

Since the structure other than the n-channel type TFT 1113, thep-channel type TFT 1114, and the n-channel type TFT 1111 is same as thatof Example 8, its description will be omitted here.

Example 10

Driver circuits and pixel portions formed by implementing the presentinvention can be used in various modules (active matrix type liquidcrystal module, active matrix type EL module and active matrix type ECmodule). That is, the present invention can be implemented in all ofelectronic equipments integrated with the modules at display portionsthereof.

As such electronic equipments, there are pointed out a video camera, adigital camera, a head mount display (goggle type display), a carnavigation system, a projector, a car stereo, a personal computer, aportable information terminal (mobile computer, cellular phone orelectronic book) and the like. Examples of these are shown in FIGS. 18and 19.

FIG. 18A shows a personal computer including a main body 2001, an imageinput portion 2002, a display portion 2003 and a keyboard 2004. Thepresent invention can be applied to the display portion 2003.

FIG. 18B shows a video camera including a main body 2101, a displayportion 2102, a voice input portion 2103, operation switches 2104, abattery 2105 and an image receiving portion 2106. The present inventioncan be applied to the display portion 2102.

FIG. 18C shows a mobile computer including a main body 2201, a cameraportion 2202, an image receiving portion 2203, an operation switch 2204and a display portion 2205. The present invention can be applied to thedisplay portion 2205.

FIG. 18D shows a goggle type display including a main body 2301, adisplay portion 2302 and an arm portion 2303. The present invention canbe applied to the display portion 2302.

FIG. 18E shows a player using a record medium recorded with programs(hereinafter, referred to as record medium) including a main body 2401,a display portion 2402, a speaker portion 2403, a record medium 2404 andan operation switch 2405. The player uses DVD (digital Versatile Disc)or CD as the record medium and can enjoy music, enjoy movie and carryout game or Internet. The present invention can be applied to thedisplay portion 2402.

FIG. 18F shows a digital camera including a main body 2501, a displayportion 2502, an eye contact portion 2503, operation switches 2504 andan image receiving portion (not illustrated). The present invention canbe applied to the display portion 2502.

FIG. 19A shows a cellular phone including a main body 2901, a soundoutput portion 2902, a sound input portion 2903, a display portion 2904,an operation switch 2905, an antenna 2906 and an image input portion(CCD, image sensor or the like) 2907. The present invention can beapplied to display portion 2904.

FIG. 19B shows a portable book (electronic book) including a main body3001, display portions 3002 and 3003, a record medium 3004, an operationswitch 3005 and an antenna 3006. The present invention can be applied todisplay portions 3002 and 3003.

FIG. 19C shows a display including a main body 3101, a support base 3102and a display portion 3103. The present invention can be applied todisplay portion 3103.

In addition, the display shown in FIG. 19C is small and medium type orlarge type, for example, screen of the display sized 5 to 20 inches.Moreover, it is preferable to mass-produce by executing a multiplepattern using a substrate sized 1×1 m to form such sized displaysection.

As has been described, the range of applying the present invention isextremely wide and is applicable to electronic equipment of all thefields. The electronic equipment of the present invention can beimplemented by freely combined with the structures in Examples 1 to 9.

Example 11

In this example, an example of using an electrophoresis display deviceas a display portion illustrated in Example 10. Typically, theelectrophoresis display device is applied to a display portion 3002 or adisplay portion 3003 of a portable book (electronic book) shown in FIG.19B.

The electrophoresis display device is also referred to as an electronicpaper. It has advantages of readability that is the same as papers, alow power consumption in comparison with other display devices, andshape of thin and light.

The electrophoresis display device can takes a various forms such asthat the plural micro capsules containing the first particle with pluselectric charge and the second particle with minus electric charge isdispersed in the solvent or solute. By applying electric field to themicro capsule, particles in the micro capsule is removed inverseddirection each other so that the color of particles gathered one sideare emitted. In addition, the first particle and the second particlecontain dyestuffs. The particles do not remove without electric field.Further, the color of the first particle and the second particle aredifferent each other (including colorless).

Thus, the electrophoresis display device uses so-called dielectricmigration effect that high dielectric invariable materials are moving tohigh electric field region. The electrophoresis display device is notnecessary a reflection plate and a opposite substrate that are necessaryfor a liquid crystal display device so that the thickness and weight arereduced by half.

Dispersed micro capsules in solvent is referred to as an electronicink.The electronicink can be printed on a surface of a glass, a plastic, acloth and a paper. Further, a color display is possible by usingparticles having a color filter and a pigment.

An active matrix type display device can be completed by providingappropriately above-mentioned plural micro capsules between twoelectrodes. If an electric field is applied to the micro capsule, thedevice can display images.

The first particle and the second particle in the micro capsule can beformed by one kind of materials or compound materials selected from thefollowing materials; conductive materials, insulating materials,semiconductor materials, magnetism materials, liquid crystal materials,ferroelectric materials, electro luminescent materials, electrochromicmaterials, and magnetic electrophoresis materials.

This Example can be freely combined with Embodiments 1 to 4, andExamples 1 to 10.

In the present invention, peeling of a substrate is carried out byphysical means, so that no damage on a semiconductor layer is caused andthe reliability of elements can be improved.

Further, the invention is capable of carrying out peeling at a highyield ratio of not only a peeled off layer with a small surface area butalso a peeled off layer with a large surface area in the entire surface.

In addition to that, the invention is made it possible to carry outpeeling easily with physical means, for example, by hands of a man, sothat the process of the invention can be said suitable for massproduction. Further, in the case a manufacturing apparatus for peeling apeeled off layer for the mass production is manufactured, even a largescale manufacturing apparatus can be manufactured at a low cost.

1. A method for peeling comprising the steps of: forming a multilayercomposed of a first material layer over a substrate and a secondmaterial layer on said first material layer over said substrate; heatingsaid multilayer so that said first material layer has a tensile stressand said second material layer has a compressive stress; and peelingsaid second material layer from said substrate after said heating stepby physical means at an interface of said first material layer and saidsecond material layers, wherein said second material layer has acompressive stress in a range of −1 to −1×10¹⁰ (Dyne/cm²) before saidpeeling step.
 2. The method according to claim 1, wherein said firstmaterial layer has a tensile stress in a range of 1 to 1×10¹⁰ (Dyne/cm²)immediately before said peeling step.
 3. A method for peeling comprisingthe steps of: forming a multilayer composed of a first material layerover a substrate and a second material layer on said first materiallayer over said substrate; heating said multilayer so that said secondmaterial layer has a compressive stress; and peeling said secondmaterial layer from said substrate after said heating step by physicalmeans at an interface of said first material layer and said secondmaterial layer, wherein said second material layer has a compressivestress in a range of −1 to −1×10¹⁰ (Dyne/cm²) before said peeling step.4. The method according to claim 3, wherein said first material layerhas a tensile stress in a range of 1 to 1×10¹⁰ (Dyne/cm²) immediatelybefore said peeling step.
 5. The method according to claim 3, whereinsaid first material layer has a compressive stress immediately aftersaid forming step and has a tensile stress immediately before saidpeeling step.
 6. A method for peeling comprising the steps of: forming amultilayer composed of a first material layer over a substrate and asecond material layer on said first material layer over said substrate;heating said multilayer so that said first material layer has a tensilestress and said second material layer has a compressive stress; stickinga supporting body to said multilayer after said heating step; andpeeling said second material layer from said substrate by physical meansat an interface of said first material layer and said second materiallayers, wherein said second material layer has a compressive stress in arange of −1 to −1×10¹⁰ (Dyne/cm²) before said peeling step.
 7. A methodfor peeling comprising the steps of: forming a multilayer composed of afirst material layer over a substrate and a second material layer onsaid first material layer over said substrate; heating said multilayerso that said second material layer has a compressive stress; sticking asupporting body to said multilayer after said heating step; and peelingsaid second material layer from said substrate by physical means at aninterface of said first material layer and said second material layers,wherein said second material layer has a compressive stress in a rangeof −1 to −1×10¹⁰ (Dyne/cm²) before said peeling step.
 8. The methodaccording to claim 7, wherein said first material layer has acompressive stress immediately after said forming step and has a tensilestress immediately before said peeling step.
 9. The method according toclaim 7, wherein said first material layer has a tensile stress in arange of 1 to 1×10¹⁰ (Dyne/cm²) immediately before said peeling step.10. The method according to claim 6, wherein said first material layerhas a tensile stress in a range of 1 to 1×10¹⁰ (Dyne/cm²) immediatelybefore said peeling step.
 11. A method for peeling comprising the stepsof: forming a multilayer composed of a first material layer over asubstrate and a second material layer provided on said first materiallayer over said substrate; heating said multilayer so that said firstmaterial layer has a tensile stress and said second material layer has acompressive stress; and peeling said second material layer from saidsubstrate after said heating step by physical means, wherein said secondmaterial layer has a compressive stress in a range of −1 to −1×10¹⁰(Dyne/cm²) before said peeling step.
 12. The method according to claim11, wherein said first material layer has a tensile stress in a range of1 to 1×10¹⁰ (Dyne/cm²) immediately before said peeling step.
 13. Amethod for peeling comprising the steps of: forming a multilayercomposed of a first material layer over a substrate and a secondmaterial layer on said first material layer over said substrate; heatingsaid multilayer so that said first material layer has a tensile stressand said second material layer has a compressive stress; sticking asupporting body to said multilayer after said heating step; and peelingsaid second material layer from said substrate by physical means,wherein said second material layer has a compressive stress in a rangeof −1 to −1×10¹⁰ (Dyne/cm²) before said peeling step.
 14. The methodaccording to claim 13, wherein said first material layer has a tensilestress in a range of 1 to 1×10¹⁰ (Dyne/cm²) immediately before saidpeeling step.
 15. The method according to claim 13, wherein said firstmaterial layer has a compressive stress immediately after said formingstep and has a tensile stress immediately before said peeling step. 16.A method for peeling comprising the steps of: forming a multilayercomposed of a first material layer having a compressive stress over asubstrate and a second material layer having a compressive stressprovided on said first material layer over said substrate; heating saidmultilayer so that said first material layer has a tensile stress andsaid second material layer has a compressive stress; and peeling saidsecond material layer from said substrate after said heating step byphysical means, wherein said second material layer has a compressivestress in a range of −1 to −1×10¹⁰ (Dyne/cm²) before said peeling step.17. The method according to claim 16, wherein said first material layerhas a tensile stress in a range of 1 to 1×10¹⁰ (Dyne/cm²) immediatelybefore said peeling step.
 18. A method for peeling comprising the stepsof: forming a multilayer composed of a first material layer having atensile stress over a substrate and a second material layer having acompressive stress provided on said first material layer over saidsubstrate; heating said multilayer so that said first material layer hasa tensile stress and said second material layer has a compressivestress; and peeling said second material layer from said substrate aftersaid heating step by physical means, wherein said second material layerhas a compressive stress in a range of −1 to −1×10¹⁰ (Dyne/cm²) beforesaid peeling step.
 19. The method according to claim 18, wherein saidfirst material layer has a tensile stress in a range of 1 to 1×10¹⁰(Dyne/cm²) immediately before said peeling step.